Identify this vertebra

Identify this vertebra

We are searching data for your request:

Forums and discussions:
Manuals and reference books:
Data from registers:
Wait the end of the search in all databases.
Upon completion, a link will appear to access the found materials.

I was walking on the beach in New Jersey (U.S.), at about 40 degrees longitude, and found this bone. It's not a fish. The long process in the front is interesting. It is likely a C2 vertebra. I looked on the web, but could not find anything aquatic that it might match. Certainly not a dolphin. It is 2 inches long (50 mm), and 2.5 inches high and wide (64 mm). I guess it need not be aquatic, and New York City (20 miles North of here) used to dump garbage in the ocean. It looks old. Can you help me identify it?

Looks like Lumbar Vertebrae or Sacral Vertebrae of a Cow like @Brian Hanson Said above.

Studying closely in laboratory can elaborate more secrets about the bones.

Cervical Vertebrae

The cervical vertebrae are the bones within the neck. The vertebrae are the bones that make up the backbone of vertebrate animals. These cervical bones are the smallest in the body in mammals, although they are not the smallest bones found within the animal. The bones are identified as C1 through C7, and they increase in size as you move down the body.

The C1 vertebra is also known as the atlas. It sits at the base of the skull and forms the atlanto-occipital joint. The next vertebra, C2, is known as the axis, and it forms the atlanto-axial joint. These are important for the movement of the head and neck, including the action of nodding.

In some species of animals, there are ribs located on the cervical vertebrae, similar to the ribs that are located on the thoracic vertebrae. These ribs can be large in some animals, such as lizard species, while they tend to be small in birds.

The cervical vertebrae are illustrated in the below image, which shows a computer-generated model of C1 through C7:


any of the separate segments comprising the spine (vertebral column). The vertebrae support the body and provide the protective bony corridor (the spinal or vertebral canal ) through which the spinal cord passes. The 33 bones that make up the spine differ considerably in size and structure according to location. There are seven cervical (neck) vertebrae, 12 thoracic (high back), five lumbar (low back), five sacral (near the base of the spine), and four coccygeal (at the base). The five sacral vertebrae are fused to form the sacrum, and the four coccygeal vertebrae are fused to form the coccyx.

The weight-bearing portion of a typical vertebra is the vertebral body, the most forward portion. This is a cylindrical structure that is separated from the vertebral bodies above and below by disks of cartilage and fibrous tissue. These intervertebral disks act as cushions to absorb the mechanical shock of walking, running, and other activity. Sometimes rupture or herniation of a disk may occur (see herniated disk ).

A semicircular arch of bone (the vertebral arch ) protrudes from the back of each vertebral body, surrounding the spinal cord. Directly in its midline a bony projection, the spinous process , grows backward from the arch. The spinous process can be felt on the back as a hard knob. Three pairs of outgrowths project from the arch. One of these protrudes horizontally on each side and in the thorax connects with the ribs. The remaining two form joints with the vertebrae above and below. The joints permit the spine to bend flexibly. The vertebrae are held firmly in place by a series of strong ligaments.

Chapter 34 - Vertebrates

  • After the evolution of the basic chordate body plan, the next major transition was the appearance of a head.
  • Chordates with a head are known as craniates.
  • The origin of a head—with a brain at the anterior end of the dorsal nerve cord, eyes and other sensory organs, and a skull—opened up a new way of feeding for chordates: active predation.

Living craniates have a set of derived characters.

  • Living craniates share a set of derived characters that distinguishes them from other chordates.
  • On the genetic level, they possess two clusters of Hox genes, while lancelets and chordates have only one.
    • Other important families of genes that produce signaling molecules and transcription factors are also duplicated in craniates.
    • This additional genetic complexity made a more complex morphology possible.
    • Neural crest cells disperse through the body and contribute to the formation of various structures, such as teeth, some of the bones and cartilages of the skull, the dermis of the face, several types of neurons, and the sensory capsules of the eyes and other sense organs.
    • The vertebrate cranium and brain (the enlarged anterior end of the dorsal, hollow nerve cord) and the anterior sensory organs are evidence of a high degree of cephalization, the concentration of sensory and neural equipment in the head.
    • Unlike the pharyngeal slits of lancelets, which are used primarily for suspension feeding, gill slits are associated with muscles and nerves that allow water to be pumped through the slits.
    • This pumping sucks in food and facilitates gas exchange.

    Cambrian fossils provide clues to craniate origins.

    • Several recent fossil finds in China of early chordates have provided information about the origin of craniates.
      • They appear to be “missing links” that straddle the transition to craniates.
      • The most primitive of these fossils is a 3-cm-long animal called Haikouella.
        • This animal resembles a lancelet and was probably a suspension feeder.
        • Haikouella also had a small but well-formed brain, eyes, and muscular segments.
        • It also had hardened structures (“denticles”) in the pharynx that may have functioned somewhat like teeth.
        • However, Haikouella did not have a skull.
        • Haikouichthys had a skull composed of cartilage and is the oldest known true craniate.

        Class Myxini: Hagfishes are the least derived craniate lineage.

        • Hagfishes have a skull of cartilage but lack jaws and vertebrae.
          • They swim in a snakelike fashion by using their segmental muscles to exert force against their notochord, which they retain in adulthood as a strong, flexible rod of cartilage.
          • They have toothlike formations made of keratin.
          • Rows of slime glands along a hagfish’s body produce small amounts of slime perhaps to repulse other scavengers or larger amounts to deter a potential predator.
          • The taxonomic term fish refers only to a specific clade of vertebrates, the actinopterygians.

          Concept 34.3 Vertebrates are craniates that have a backbone

          • During the Cambrian period, a lineage of craniates evolved into vertebrates.
          • With a more complex nervous system and a more elaborate skeleton, vertebrates became active predators.
          • After vertebrates branched off from other craniates, they underwent another genetic duplication, this one involving a group of transcription factor genes called the Dlx family.
          • This additional genetic complexity was associated with innovations in vertebrate nervous systems and skeletons, including a more extensive skull and a backbone composed of vertebrae.
          • In the majority of vertebrates, the vertebrae enclose the spinal cord and have taken over the biomechanical roles of the notochord.
          • Aquatic vertebrates also have a number of adaptations associated with faster swimming, including fins stiffened by fin rays and a more efficient gas exchange system in the gills.

          Class Cephalaspidomorphi: Lampreys are the oldest living lineage of vertebrates.

          • Like hagfishes, lampreys offer clues to early chordate evolution but also have acquired unique characters.
          • There are about 35 species of lampreys inhabiting both marine and freshwater environments.
            • Most lampreys are parasites that feed by clamping a round, jawless mouth onto a fish.
            • They use their rasping tongues to penetrate the skin of their fish prey and to ingest the prey’s blood.
            • These larvae resemble lancelets and live partially buried in sediment.
            • After metamorphosis, these lampreys attain sexual maturity, reproduce, and die within a few days.
            • Unlike most vertebrate cartilage, lamprey cartilage contains no collagen. Instead, it is a stiff protein matrix.
            • Lampreys also have a cartilaginous pipe surrounding the rodlike notochord.
            • Pairs of cartilaginous projections extend dorsally, partially enclosing the nerve cord with what might be a vestige of an early-stage vertebral column.

            Many vertebrate lineages emerged early.

            • Conodonts were slender, soft-bodied vertebrates with prominent eyes.
              • At the anterior end of their mouth, they had a set of barbed hooks made of mineralized dental tissue.
              • They probably hunted with their large eyes and impaled their prey on hooks.
              • The food then passed to the pharynx, where a different set of dental elements crushed and sliced it.
              • These vertebrates had paired fins and an inner ear with two semicircular canals that provided a sense of balance.
              • Its mineralization began only after lampreys diverged from other vertebrates.
              • Mineralization may have been associated with the transition to new feeding mechanisms.
              • Only in more derived vertebrates did the endoskeleton begin to mineralize, starting with the skull.

              Concept 34.4 Gnathostomes are vertebrates that have jaws

              • The gnathostomes have true jaws, hinged structures that enable vertebrates to grasp food firmly.
                • According to one hypothesis, gnathostome jaws evolved by modification of the skeletal rods that had previously supported the anterior pharyngeal gill slits.
                • The remaining gill slits were no longer required for suspension feeding and remained as the major sites of respiratory gas exchange.

                Gnathostomes have a number of shared, derived characters.

                • Gnathostomes share other derived characters besides jaws.
                • The common ancestors of all gnathostomes underwent an additional duplication of the Hox genes, so that the single cluster present in early chordates became four.
                  • Other gene clusters also duplicated, allowing further complexity in the development of gnathostome embryos.
                  • Jaws, with the help of teeth, enable the animal to grip food items firmly and slice them up.
                  • Paired fins, along with the tail, enable fishes to maneuver accurately while swimming.
                  • Most placoderms were less than a meter long, although some giants were more than 10 m long.

                  Class Chondrichthyes: Sharks and rays have cartilaginous skeletons.

                  • The class Chondrichthyes, sharks and their relatives, includes some of the biggest and most successful vertebrate predators in the oceans.
                  • Chondrichthyes have relatively flexible endoskeletons of cartilage rather than bone.
                    • In most species, parts of the skeleton are impregnated by calcium.
                    • Traces of bone can be found in living chondrichthyes, in their scales, at the base of their teeth and (in some sharks) in a thin layer on the surface of their vertebrae.
                    • The loss of bone in chondrichthyes is a derived condition, which emerged after they diverged from other gnathostomes.
                    • All have well-developed jaws and paired fins.
                    • Powerful axial muscles power undulations of the body and caudal fin to drive the fish forward.
                    • The dorsal fins provide stabilization.
                    • While some buoyancy is provided by low-density oils in the large liver, the flow of water over the pectoral and pelvic fins also provides lift to keep the animal suspended in the water column.
                    • Some sharks and many skates and rays spend much time resting on the seafloor, using the muscles of their jaws and pharynx to pump water over the gills.
                    • In contrast, the largest sharks and rays are suspension feeders that consume plankton.
                    • Sharks have several rows of teeth that gradually move to the front of the mouth as old teeth are lost.
                    • Within the intestine of a shark is a spiral valve, a corkscrew-shaped ridge that increases surface area and prolongs the passage of food along the short digestive tract.
                    • Sharks have sharp vision but cannot distinguish colors.
                    • Their acute olfactory sense (smelling) occurs in a pair of nostrils that do not function in breathing.
                    • Sharks can detect electrical fields, including those generated by the muscle contractions of nearby prey, through patches of specialized skin pores.
                    • The lateral line system, a row of microscopic organs sensitive to pressure changes, can detect low-frequency vibrations.
                    • In sharks, the whole body transmits sound to the hearing organs of the inner ear.
                    • Males transfer sperm via claspers on their pelvic fins to the reproductive tract of the female.
                    • Oviparous sharks encase their eggs in protective cases and lay them outside the mother’s body.
                      • These hatch months later as juveniles.
                      • The embryo completes development in the uterus, nourished by the egg yolk.
                      • Most rays are flattened bottom dwellers that crush molluscs and crustaceans in their jaws.
                      • The enlarged pectoral fins of rays are used like wings to propel the animal through the water.
                      • The tail of many rays is whiplike and may bear venomous barbs for defense against threats.
                      • They are severely threatened by overfishing.
                      • In 2003, researchers reported that shark stocks in the northwest Atlantic declined 75% in 15 years.

                      Osteichthyes: The extant classes of bony fishes are the ray-finned fishes, the lobe-finned fishes, and the lungfishes.

                      • The vast majority of bony fishes belong to a clade of gnathostomes called the Osteichthyes (meaning “bony fish”).
                      • Systematists today include tetrapods with bony fish in Osteichthyes, which otherwise would be paraphyletic.
                      • Nearly all bony fishes have an ossified endoskeleton with a hard matrix of calcium phosphate.
                        • It is not clear when the shift to a bony skeleton took place during gnathostome evolution.
                        • Water is drawn into the mouth, through the pharynx, and out between the gills by movements of the operculum and muscles surrounding the gill chambers.
                        • The positive buoyancy provided by air counters the negative buoyancy of the tissues, enabling many fishes to be neutrally buoyant and remain suspended in the water.
                        • The swim bladder evolved from balloonlike lungs that may have been used to breathe air when dissolved oxygen levels were low in stagnant shallow waters.
                        • Most species are oviparous, reproducing by external fertilization after the female sheds large numbers of small eggs.
                        • Internal fertilization and birthing characterize other species.
                        • This class includes bass, trout, perch, tuna, and herring.
                        • In this group, the fins are supported by long, flexible rays.
                        • The fins may be modified for maneuvering, defense, and other functions.
                        • Many species of ray-finned fishes returned to fresh water at some point in their evolution.
                        • Some ray-finned fishes, such as salmon, make a round-trip from fresh water to seawater and back to fresh water during their life cycle.
                        • Many Devonian lobe-fins were large, bottom dwellers that may have used their paired, muscular fins to “walk” along the bottom.
                        • By the end of the Devonian period, lobe-fin diversity was dwindling.
                        • One lineage, the coelacanths (class Actinistia) probably originated as freshwater animals with lungs, but others shifted to the ocean, including the only living genus, Latimeria.
                        • The second lineage of living lobe-fins is represented by three genera of lungfishes (class Dipnoi), which live today in the Southern Hemisphere.
                          • They generally inhabit stagnant ponds and swamps.
                          • They can gulp air into lungs connected to the pharynx of the digestive tract to provide oxygen for metabolism.
                          • Lungfishes also have gills, which are the main organs for gas exchange in Australian lungfishes.
                          • When ponds shrink during the dry season, some lungfishes can burrow into the mud and estivate.

                          Concept 34.5 Tetrapods are gnathostomes that have limbs and feet

                          • One of the most significant events in vertebrate history took place 360 million years ago, when the fins of some lobe-fins evolved into tetrapod limbs and feet.
                          • The most significant character of tetrapods is the four limbs, which allow them to support their weight on land.
                            • The feet of tetrapods have digits that allow them to transmit muscle-generated forces to the ground when they walk.
                            • The ears are adapted to the detection of airborne sounds.
                            • At the water’s edge, leglike appendages were probably better equipment than fins for paddling and crawling through the dense vegetation in shallow water.
                            • The tetrapod body plan was thus a modification of a preexisting body plan.
                            • For example, fossils of Acanthostega from 365 million years ago had bony gill supports and rays in its tail to support propulsion in water, but it also had fully formed legs, ankles, and digits.
                            • Acanthostega is representative of a period of vertebrate evolution when adaptations for shallow water allowed certain fishes to make a gradual transition to the terrestrial side of the water’s edge.
                            • Judging from the morphology and location of the fossils, most of these early tetrapods remained tied to water.

                            Class Amphibia: Salamanders, frogs, and caecilians are the three extant amphibian orders.

                            • Today the amphibians (class Amphibia) are represented by about 4,800 species of salamanders (order Urodela, “tailed ones”), frogs (order Anura, “tail-less ones”), and caecilians (order Apoda, “legless ones”).
                            • Some of the 500 species of urodeles are entirely aquatic, but others live on land as adults or throughout life.
                              • On land, most salamanders walk with a side-to-side bending of the body that may resemble the swagger of the early terrestrial tetrapods.
                              • Adult frogs use powerful legs to hop along the terrain.
                              • Frogs nab insects by flicking out their sticky tongues, which are attached to the front of the mouth.
                              • Many poisonous species are brightly colored, perhaps to warn predators who associate the coloration with danger.
                              • The reduction of legs evolved secondarily from a legged ancestor.
                              • A few South American species live in freshwater ponds and streams.
                              • Tadpoles are usually aquatic herbivores with gills and a lateral line system, and they swim by undulating their tails.
                              • During metamorphosis, the tadpole develops legs, the lateral line disappears, and lungs replace gills.
                              • Adult frogs are carnivorous hunters.
                              • There are some strictly aquatic, and some strictly terrestrial frogs, salamanders, and caecilians.
                              • The larvae of salamanders and caecilians look like adults and are also carnivorous.
                              • For example, the mudpuppy (Necturus) retains gills and other larval features when sexually mature.
                              • Those adapted to drier habitats spend much of their time in burrows or under moist leaves where the humidity is higher.
                              • Most amphibians rely heavily on their moist skin to carry out gas exchange with the environment.
                                • Some terrestrial species lack lungs entirely and breathe exclusively through their skin and oral cavity.
                                • Most species have external fertilization, with eggs shed in ponds or swamps or at least in moist environments.
                                • Some species lay vast numbers of eggs in temporary pools where mortality is high.
                                • Others display various types of parental care and lay relatively few eggs.
                                  • In some species, males or females may house eggs on the back, in the mouth, or even in the stomach.
                                  • Some species are ovoviviparous or viviparous, retaining the developing eggs in the female reproductive tract until released as juveniles.
                                  • Then many male frogs fill the air with their mating calls as they defend breeding territories or attract females.
                                  • In some terrestrial species, migrations to specific breeding sites may involve vocal communication, celestial navigation, or chemical signaling.
                                  • Acid precipitation is damaging to amphibians because of their dependence on wet places for completion of their life cycles.

                                  Concept 34.6 Amniotes are tetrapods that have a terrestrially adapted egg

                                  • The amniote clade consists of the mammals and reptiles (including birds).
                                  • The evolution of amniotes from an amphibian ancestor involved many adaptations for terrestrial living.
                                  • The amniotic egg is the major derived character of the clade.
                                  • Inside the shell of the amniotic egg are several extraembryonic membranes that function in gas exchange, waste storage, and the transfer of stored nutrients to the embryo.
                                    • The amniotic egg is named for one of these membranes, the amnion, which encloses a fluid-filled “private pond” that bathes the embryo and acts as a hydraulic shock absorber.
                                    • In contrast to the shell-less eggs of amphibians, the amniotic eggs of most amniotes have a shell that retains water and can be laid in a dry place.
                                    • The calcareous shells of bird eggs are inflexible, while the leathery eggs of many reptiles are flexible.
                                    • Most mammals have dispensed with the shell.
                                      • The embryo implants in the wall of the uterus and obtains its nutrition from the mother.
                                      • No fossils of amniotic eggs have been found from that time.

                                      The reptile clade includes birds.

                                      • The reptile clade includes tuatara, lizards, snakes, turtles, crocodilians, and birds, as well as extinct groups such as dinosaurs.
                                      • Reptiles have several adaptations for terrestrial life not generally found in amphibians.
                                        • Scales containing the protein keratin waterproof the skin, preventing dehydration in dry air.
                                          • Crocodiles, which are adapted to water, have evolved more permeable scales called scutes.
                                          • As an exception, many turtles can use the moist surfaces of their cloaca for gas exchange.
                                          • Fertilization occurs internally, before the shell is secreted as the egg passes through the female’s reproductive tract.
                                          • Some species of lizards and snakes are viviparous, with their extraembryonic membranes forming a placenta that enables the embryo to obtain nutrients from its mother.
                                          • However, many nonbird reptiles regulate their body temperature behaviorally by basking in the sun when cool and seeking shade when hot.
                                          • One advantage of this strategy is that an ectothermic reptile can survive on less than 10% of the calories required by a mammal of equivalent size.
                                          • Birds are endothermic, capable of keeping the body warm through metabolism.
                                          • Some parareptiles had dermal plates on their skin, which may have provided defense against predators.
                                          • The most obvious derived character of diapsids is a pair of holes on each side of the skull, behind the eye socket.
                                          • One, the lepidosaurs, includes lizards, snakes, and tuataras.
                                            • This lineage also produced a number of marine reptiles including plesiosaurs and ichthyosaurs.
                                            • The pterosaur wing is formed from a bristle-covered membrane of skin that stretched between the hind leg and the tip of an elongated finger.
                                            • Well-preserved fossils show the presence of muscles, blood vessels, and nerves in the wing membrane, suggesting that pterosaurs could dynamically adjust their membranes to assist their flight.
                                            • There were two main dinosaur lineages: the ornithischians, which were mostly herbivorous, and the saurischians, which included both long-necked giant herbivores and bipedal carnivorous theropods.
                                              • Theropods included the famous Tyrannosaurus rex as well as the ancestors of birds.
                                              • Paleontologists have discovered signs of parental care among dinosaurs.
                                              • Some experts are skeptical.
                                              • In the warm, consistent Mesozoic climate, behavioral adaptations may have been sufficient for maintaining a suitable body temperature for terrestrial dinosaurs.
                                              • Also, the low surface-to-volume ratios would have reduced the effects of daily fluctuations in air temperature on the animal’s internal temperature.
                                              • Some anatomical evidence supports the hypothesis that at least some dinosaurs were endotherms.
                                                • Paleontologists have found fossils of dinosaurs in both Antarctica and the Arctic, although the climate in those areas was milder during the Mesozoic than today.
                                                • It is uncertain whether dinosaurs were declining before they were finished off by an asteroid or comet impact.
                                                • Tuatara relatives lived at least 220 million years ago, when they thrived on every continent well into the Cretaceous period.
                                                • Most are relatively small, but they range in length from 16 mm to 3 m.
                                                • However, recently discovered fossils of aquatic snakes with complete hind legs suggest that snakes likely evolved in water and then recolonized land.
                                                • Some species of snakes retain vestigial pelvic and limb bones, providing evidence of their ancestry.
                                                • Snakes have acute chemical sensors and are sensitive to ground vibrations.
                                                  • The flicking tongue fans odors toward olfactory organs on the roof of the mouth.
                                                  • The origin of the turtle shell remains a puzzle.
                                                    • Some paleontologists suggest that turtle shells evolved from the dermal shells of parareptiles.
                                                    • They spend most of their time in water, breathing air through upturned nostrils.
                                                    • Crocodilians are confined to the tropics and subtropics.

                                                    Birds evolved as feathered dinosaurs.

                                                    • Like crocodilians, birds are archosaurs, but highly specialized for flight.
                                                      • In addition to amniotic eggs and scales, modern birds have feathers and other distinctive flight equipment.
                                                      • One adaptation to reduce weight is the absence of some organs.
                                                        • For instance, females have only one ovary.
                                                        • The bones are air-filled and honeycombed to reduce weight without sacrificing much strength.
                                                        • Feathers are made of beta-keratin, a protein similar to the keratin of reptile scales.
                                                        • Flight enhances hunting and scavenging.
                                                          • It enables many birds to exploit flying insects, an abundant, highly nutritious food resource.
                                                          • Birds are endothermic, using their own metabolic heat to maintain a constant body temperature.
                                                            • Feathers and, in some species, a layer of fat provide insulation.
                                                            • The lungs have tiny tubes leading to and from elastic air sacs that help dissipate heat and reduce body density.
                                                            • The large brains of birds (proportionately larger than those of reptiles or amphibians) support very complex behavior.
                                                            • This culminates in copulation, contact between the mates’ vents, the openings to their cloacae.
                                                            • After eggs are laid, the avian embryo is kept warm through brooding by the mother, father, or both, depending on the species.
                                                            • These fossils suggest that feathers evolved long before feathered flight, possibly for insulation or courtship.
                                                            1. Small ground-running dinosaurs chasing prey or evading predation may have used feathers to gain extra lift as they jumped into the air.
                                                            2. Dinosaurs could have glided from trees, aided by feathers.
                                                            • This ancient bird lived about 150 million years ago, during the late Jurassic period.
                                                            • Archaeopteryx had clawed forelimbs, teeth, and a long tail containing vertebrae.
                                                              • Without its feathers, Archaeopteryx would probably be classified as a theropod dinosaur.
                                                              • Its skeletal anatomy indicates that it was a weak flyer, perhaps a tree-dwelling glider.
                                                              • The ratites include the ostrich, kiwi, and emu.
                                                              • They have powerful pectoral muscles, which they use in swimming.
                                                              • The beak of birds is very adaptable, taking on a great variety of shapes for different diets.

                                                              Concept 34.7 Mammals are amniotes that have hair and produce milk

                                                              Mammals diversified extensively in the wake of the Cretaceous extinctions.

                                                              • Mammals have a number of derived traits.
                                                                • All mammalian mothers use mammary glands to nourish their babies with milk, a balanced diet rich in fats, sugars, proteins, minerals, and vitamins.
                                                                • All mammals also have hair, made of keratin.
                                                                  • Hair and a layer of fat under the skin retain metabolic heat, contributing to endothermy in mammals.
                                                                  • Adaptations include a muscular diaphragm and a four-chambered heart.
                                                                  • Many species are capable of learning.
                                                                  • The relatively long period of parental care extends the time for offspring to learn important survival skills by observing their parents.
                                                                  • Unlike the uniform conical teeth of most reptiles, the teeth of mammals come in a variety of shapes and sizes adapted for processing many kinds of foods.
                                                                  • During the evolution of mammals from reptiles, two bones formerly in the jaw joint were incorporated into the mammalian ear and the jaw joint was remodeled.
                                                                  • Synapsids have a temporal fenestra behind the eye socket on each side of the skull.
                                                                  • These animals were not mammals, but they were small and likely hairy, fed on insects at night, and had a higher metabolism that other synapsids.
                                                                  • They likely laid eggs.
                                                                  • Early mammals diversified into a number of lineages, all about the size of a shrew.
                                                                  • Modern mammals are split into three groups: monotremes (egg-laying mammals), marsupials (mammals with pouches), and eutherian (placental) mammals.
                                                                  • The reptile-like egg contains enough yolk to nourish the developing embryo.
                                                                  • After hatching, the baby sucks milk from the mother’s fur because she lacks nipples.
                                                                  • In most species, the tiny offspring climbs from the exit of the female’s reproductive tract to the mother’s pouch.
                                                                  • In Australia, marsupials have radiated and filled niches occupied by eutherian mammals in other parts of the world.
                                                                    • Through convergent evolution, these diverse marsupials resemble eutherian mammals that occupy similar ecological roles.
                                                                    • Australia’s isolation facilitated the diversification and survival of its marsupial fauna.
                                                                    • Invasions of placental mammals from North America impacted the marsupial fauna of South America about 12 million years ago and then again about 3 million years ago when the continents were connected by the Isthmus of Panama.
                                                                      • This mammalian biogeography is an example of the interplay between biological and geological evolution.
                                                                      • Young eutherians complete their embryonic development within the uterus, joined to the mother by the placenta.
                                                                      • Eutherians are commonly called placental mammals because their placentas are more complex than those of marsupials and provide a more intimate and long-lasting association between mother and young.

                                                                      Concept 34.8 Humans are bipedal hominoids with a large brain

                                                                      Primate evolution provides a context for understanding human origins.

                                                                      • Primates include lemurs, monkeys, and apes.
                                                                      • Primates have large brains and short jaws.
                                                                      • Their eyes are forward-looking.
                                                                      • Most primates have hands and feet adapted for grasping.
                                                                      • Relative to other mammals, they have large brains and short jaws.
                                                                      • They have flat nails on their digits, rather than narrow claws.
                                                                      • Primates also have relatively well-developed parental care and relatively complex social behavior.
                                                                      • The earliest primates were probably tree dwellers, shaped by natural selection for arboreal life.
                                                                        • The grasping hands and feet of primates are adaptations for hanging on to tree branches.
                                                                          • All modern primates, except Homo, have a big toe that is widely separated from the other toes.
                                                                          • The thumb is relatively mobile and separate from the fingers in all primates, but a fully opposable thumb is found only in anthropoid primates.
                                                                          • The unique dexterity of humans, aided by distinctive bone structure at the thumb base, represents descent with modification from ancestral hands adapted for life in the trees.
                                                                          • The overlapping fields of vision of the two eyes enhance depth perception, an obvious advantage when brachiating.
                                                                          • Excellent hand-eye coordination is also important for arboreal maneuvering.
                                                                          • The Prosimii (prosimians) probably resemble early arboreal primates and include the lemurs of Madagascar and the lorises, pottos, and tarsiers of tropical Africa and southern Asia.
                                                                          • The Anthropoidea (anthropoids) include monkeys, apes, and humans.
                                                                          • The Old World and New World monkeys underwent separate adaptive radiations.
                                                                          • All New World monkeys are arboreal, but Old World monkeys include arboreal and ground-dwelling species.
                                                                          • Most monkeys in both groups are diurnal, and usually live in bands held together by social behavior.
                                                                          • Modern apes are confined exclusively to the tropical regions of the Old World.
                                                                          • They evolved from Old World monkeys about 20–25 million years ago.
                                                                          • Only gibbons and orangutans are primarily arboreal.
                                                                          • Apes have relatively larger brains than monkeys, and their behavior is more flexible.

                                                                          Humans are bipedal hominoids.

                                                                          • In the continuity of life spanning more than 3.5 billion years, humans and apes have shared ancestry for all but the past few million years.
                                                                          • Human evolution is marked by the evolution of several major features.
                                                                            • Humans stand upright and walk on two legs.
                                                                            • Humans have a much larger brain than other hominoids and are capable of language, symbolic thought, and tool use.
                                                                            • Humans have reduced jawbones and muscles and a shorter digestive tract.
                                                                            • Human and chimpanzee genomes are 99% identical.
                                                                              • Scientists are comparing the genomes of humans and chimpanzees to investigate the 1% difference.
                                                                              • These species are known as hominids.
                                                                              • Sahelanthropus and other early hominids shared some of the derived characters of humans.
                                                                              • They had reduced canine teeth and relatively flat faces.
                                                                              • They were more upright and bipedal than other hominoids.
                                                                              • Early hominids were small in stature, with relatively large teeth and a protruding lower jaw.
                                                                              1. First, our ancestors were not chimpanzees or any other modern apes.
                                                                                • Chimpanzees and humans represent two divergent branches of the hominoid tree that evolved from a common ancestor that was neither a chimpanzee nor a human.
                                                                              2. Second, human evolution did not occur as a ladder with a series of steps leading directly from an ancestral hominoid to Homo sapiens.
                                                                                • If human evolution is a parade, then many splinter groups traveled down dead ends, and several different human species coexisted.
                                                                                • Human phylogeny is more like a multibranched bush with our species as the tip of the only surviving twig.
                                                                              3. Third, the various human characteristics, such as upright posture and an enlarged brain, did not evolve in unison.
                                                                              4. Different features evolved at different rates, called mosaic evolution.
                                                                              5. Our pedigree includes ancestors who walked upright but had brains much less developed than ours.
                                                                              • The first australopith, A. africanus, was discovered in 1924 by Raymond Dart in a quarry in South Africa.
                                                                                • From this and other skeletons, it became clear that A. africanus probably walked fully erect and had humanlike hands and teeth.
                                                                                • However, the brain was only about one-third the size of a modern human’s brain.
                                                                                • This fossil, nicknamed “Lucy,” was described as a new species, A. afarensis.
                                                                                • However, the pelvis and skull bones and fossil tracks showed that A. afarensis walked bipedally.
                                                                                • Two lineages appeared after A. afarensis: the “robust” australopithecines with sturdy skulls and powerful jaws and teeth for grinding and chewing hard, tough foods and the “gracile” australopithecines with lighter feeding equipment adapted for softer foods.
                                                                                • Our anthropoid ancestors of 30–35 million years ago were tree dwelling.
                                                                                  • Twenty million years ago, the forests contracted as the climate became drier.
                                                                                  • The result was an increased savanna with few trees.
                                                                                  • For decades, paleontologists thought that bipedalism was an adaptation to life on the savanna.
                                                                                  • When and why did tool use arise in the human lineage?
                                                                                  • Other hominoids are capable of sophisticated tool use.
                                                                                    • Orangutans can fashion probes from sticks for retrieving insects from their nests.
                                                                                    • Chimps use rocks to smash open food and put leaves on their feet to walk over thorns.
                                                                                    • The australopith fossils near the site had relatively small brains.
                                                                                    • Perhaps tool use originated before large hominid brains evolved.
                                                                                    • These fossils range in age from 2.4 to 1.6 million years old.
                                                                                    • This species had less prognathic jaws and larger brains (about 600–750 cm3) than australopiths.
                                                                                    • In some cases, anthropologists have found sharp stone tools with these fossils, indicating that some hominids had started to use their brains and hands to fashion tools.
                                                                                    • H. ergaster had a larger brain than Homo habilis, as well as long slender legs well adapted for long-distance walking.
                                                                                    • This species lived in more-arid environments and was associated with more-sophisticated tool use.
                                                                                    • Its reduced teeth suggest that it might have been able to cook or mash its food before eating it.
                                                                                    • Sexual dimorphism is reduced in pair-bonding species.
                                                                                    • Male and female Homo ergaster may have engaged in more pair-bonding than earlier hominids, perhaps in order to provide long-term biparental care of babies.
                                                                                    • They lived from about 1.8 million to 500,000 years ago.
                                                                                      • Fossils from Asia are known by such names as “Beijing man” and “Java Man.”
                                                                                      • In Europe, Neanderthals arose from an earlier species, Homo heidelbergensis, which arose in Africa about 600,000 years ago and spread to Europe.
                                                                                      • Fossilized skulls indicate that Neanderthals had brains as large as ours, though somewhat different in shape.
                                                                                      • They made hunting tools from stone and wood.
                                                                                      • Neanderthals were generally more heavily built than modern humans.
                                                                                      • Scientists have extracted DNA from four fossil Neanderthals living at different times and places in Europe.
                                                                                        • All Neanderthals formed a clade, while modern Europeans were more closely related to modern Africans and Asians.
                                                                                        • These early humans were slender and lacked brow ridges.
                                                                                        • This is supported by analysis of mDNA and Y chromosomes of various populations.
                                                                                        • Neanderthals produced sophisticated tools, but had little creativity or capacity for symbolic thought.
                                                                                        • Comparisons of flanking regions of the gene suggest that most changes took place within the past 200,000 years.
                                                                                        • The evolutionary change in FOXP2 may be the first genetic clue about how our own species came to be.

                                                                                        Lecture Outline for Campbell/Reece Biology, 7th Edition, © Pearson Education, Inc. 34-1

                                                                                        Vertebral column

                                                                                        Our editors will review what you’ve submitted and determine whether to revise the article.

                                                                                        Vertebral column, also called spinal column, spine, or backbone, in vertebrate animals, the flexible column extending from neck to tail, made of a series of bones, the vertebrae. The major function of the vertebral column is protection of the spinal cord it also provides stiffening for the body and attachment for the pectoral and pelvic girdles and many muscles. In humans an additional function is to transmit body weight in walking and standing.

                                                                                        Each vertebra, in higher vertebrates, consists of a ventral body, or centrum, surmounted by a Y-shaped neural arch. The arch extends a spinous process (projection) downward and backward that may be felt as a series of bumps down the back, and two transverse processes, one to either side, which provide attachment for muscles and ligaments. Together the centrum and neural arch surround an opening, the vertebral foramen, through which the spinal cord passes. The centrums are separated by cartilaginous intervertebral disks, which help cushion shock in locomotion.

                                                                                        Vertebrae in lower vertebrates are more complex, and the relationships of their parts to those of higher animals are often unclear. In primitive chordates (e.g., amphioxus, lampreys) a rodlike structure, the notochord, stiffens the body and helps protect the overlying spinal cord. The notochord appears in the embryos of all vertebrates in the space later occupied by the vertebral bodies—in some fish it remains throughout life, surrounded by spool-shaped centrums in other vertebrates it is lost in the developed animal. In primitive chordates the spinal cord is protected dorsally by segmented cartilages—these foreshadow the development of the neural arch of true vertebrae.

                                                                                        Fish have trunk and caudal (tail) vertebrae in land vertebrates with legs, the vertebral column becomes further subdivided into regions in which the vertebrae have different shapes and functions. Crocodilians and lizards, birds, and mammals demonstrate five regions: (1) cervical, in the neck, (2) thoracic, in the chest, which articulates with the ribs, (3) lumbar, in the lower back, more robust than the other vertebrae, (4) sacral, often fused to form a sacrum, which articulates with the pelvic girdle, (5) caudal, in the tail. The atlas and axis vertebrae, the top two cervicals, form a freely movable joint with the skull.

                                                                                        The numbers of vertebrae in each region and in total vary with the species. Snakes have the greatest number, all very similar in type. In turtles some vertebrae may be fused to the shell (carapace) in birds all but the cervical vertebrae are usually fused into a rigid structure, which lends support in flight. Most mammals have seven cervical vertebrae size rather than number account for the variations in neck length in different species. Whales show several specializations—the cervical vertebrae may be either much reduced or much increased in number, and the sacrum is missing. Humans have 7 cervical, 12 thoracic, 5 lumbar, 5 fused sacral, and 3 to 5 fused caudal vertebrae (together called the coccyx).

                                                                                        The vertebral column is characterized by a variable number of curves. In quadrupeds the column is curved in a single arc (the highest portion occurring at the middle of the back), which functions somewhat like a bow spring in locomotion. In humans this primary curve is modified by three more: (1) a sacral curve, in which the sacrum curves backward and helps support the abdominal organs, (2) an anterior cervical curve, which develops soon after birth as the head is raised, and (3) a lumbar curve, also anterior, which develops as the child sits and walks. The lumbar curve is a permanent characteristic only of humans and their bipedal forebears, though a temporary lumbar curve appears in other primates in the sitting position. The cervical curve disappears in humans when the head is bent forward but appears in other animals as the head is raised.

                                                                                        In humans the structure and function of the vertebral column can be affected by certain diseases, disorders, or injuries. Examples include scoliosis, lordosis, and kyphosis, which are deviations from the normal spinal curvature degenerative diseases, such as osteoarthritis and Baastrup disease (kissing spine syndrome) and tuberculosis of the spine (Pott disease), which is caused by infection of the vertebral column by Mycobacterium tuberculosis.

                                                                                        The Editors of Encyclopaedia Britannica This article was most recently revised and updated by Kara Rogers, Senior Editor.

                                                                                        Clinical Relevance: Abnormal Morphology of the Spine

                                                                                        Fig 9 – Radiograph of scoliosis of the spine.

                                                                                        There are several clinical syndromes resulting from an abnormal curvature of the spine:

                                                                                        • Kyphosis – excessive thoracic curvature, causing a hunchback deformity.
                                                                                        • Lordosis – excessive lumbar curvature, causing a swayback deformity.
                                                                                        • Scoliosis – lateral curvature of the spine, usually of unknown cause.
                                                                                        • Cervical spondylosis – decrease in the size of the intervertebral foramina, usually due to degeneration of the joints of the spine. The smaller size of the intervertebral foramina puts pressure on the exiting nerves, causing pain.

                                                                                        Try again to score 100%. Use the information in this article to help you with the answers.

                                                                                        Our 3D anatomical model provides you with hands-on, interactive and valuable learning tool right here on your device. To access the TeachMeAnatomy 3D Model, you must be a premium subscriber.

                                                                                        The vertebral column is a series of approximately 33 bones called vertebrae, which are separated by intervertebral discs.

                                                                                        The column can be divided into five different regions, with each region characterised by a different vertebral structure.

                                                                                        In this article, we shall look at the anatomy of the vertebral column - its function, structure, and clinical significance.

                                                                                        Vertebral Column Quiz for Anatomy

                                                                                        1. How many cervical vertebrae are there?

                                                                                        The answer is C, 7. These vertebrae make up the cervical spine in the neck, and they are numbered C1-C7.

                                                                                        2. The bones of the vertebral column are classified as which type of bone?

                                                                                        The answer is B, irregular. Anatomists classify these bones as irregular bones.

                                                                                        3. How many thoracic vertebrae are there?

                                                                                        The answer is A, 12. Remember, these articulate with the 12 pairs of ribs, so that will help you remember the number.

                                                                                        4. How many lumbar vertebrae are there?

                                                                                        The answer is C, 5. There are 5 lumbar vertebrae, which are denser than the preceding vertebrae.

                                                                                        5. How many bones are there in the vertebral column?

                                                                                        The answer is D, both A and B are correct. There are 33 bones in the vertebral column of an infant, but some of these bones later fuse to form the coccyx and sacrum, leaving an average adult with 26 bones in the vertebral column.

                                                                                        6. Which statement is true?

                                                                                        A. The sacrum consists of 5 fused vertebrae.

                                                                                        B. The coccyx consists of 3-5 fused vertebrae.

                                                                                        C. There are five main regions in the vertebral column

                                                                                        The answer is D, all of the above statements are true.

                                                                                        7. Which vertebral regions feature primary (kyphotic) curves?

                                                                                        A. The thoracic and sacral curvatures

                                                                                        B. The cervical and lumbar curvatures

                                                                                        The answer is A, thoracic and sacral curvatures. These curves are convex, curving outward toward the backside of the body.

                                                                                        8. Which vertebral regions feature secondary (lordotic) curves?

                                                                                        A. The thoracic and sacral curvatures

                                                                                        B. the cervical and lumbar curvatures

                                                                                        The answer is B, the cervical and lumbar curvatures. These curve inwardly toward the front of the body.

                                                                                        9. Which part of the intervertebral disc contains layers of rings?

                                                                                        The answer is B, annulus fibrosus. This is the fibrous ring part that surround the gel-like nucleus, which is called the nucleus pulposis.

                                                                                        10. All of the vertebrae are cushioned by intervertebral discs.

                                                                                        The answer is B, false. While intervertebral discs do cushion the vertebrae, not all vertebrae have them. There is no intervertebral disc between C1 and C2, or between the sacrum and coccyx bones.

                                                                                        Don’t forget to tell your friends about this quiz by sharing it your Facebook, Twitter, and other social media. You can also take more fun nursing quizzes.

                                                                                        Circulatory System Adaptations for Oxygenation in the Fetus

                                                                                        While a fetus is in utero the exchange of oxygen, nutrients,and waste products occurs across the placenta.  Because the digestive tract, lungs and kidneys of the fetus will not begin to function until after birth, the fetal circulation has been modified to adjust blood flow to these organs.    Oxygenated blood is brought to the fetal heart through the umbilical cord via the umbilical vein, and then the inferior vena cava.

                                                                                        Follow the umbilical vein, transected earlier in the dissection, as it seems to disappear in the liver.  In Figure 7.5 notice how the umbilical vein divides into two branches before reaching the liver. One branch heads to the liver while the other (called the ductus venosis) shunts about 50% of the oxygenated blood directly to the inferior/anterior vena cava and thus to the fetal heart. The blood entering the liver is eventually directed to the vena cava through the hepatic veins. After birth the umbilical vein and umbilical arteries atrophy and the ductus venosus gradually fills with connective tissue and closes (ligamentum venosum). This is one of three modifications to the fetal circulatory system. 

                                                                                        Because the lungs are not functioning in the fetus, two modifications to the circulation are found within the heart:  The ductus arteriosus and the foramen ovale.  We will look at these two modifications more closely when dissecting the calf heart.

                                                                                        Fig. 7.5. Organization of the fetal circulation of the pig. The most highly oxygenated blood is indicated by hatch marks.

                                                                                        DMCA Complaint

                                                                                        If you believe that content available by means of the Website (as defined in our Terms of Service) infringes one or more of your copyrights, please notify us by providing a written notice (“Infringement Notice”) containing the information described below to the designated agent listed below. If Varsity Tutors takes action in response to an Infringement Notice, it will make a good faith attempt to contact the party that made such content available by means of the most recent email address, if any, provided by such party to Varsity Tutors.

                                                                                        Your Infringement Notice may be forwarded to the party that made the content available or to third parties such as

                                                                                        Please be advised that you will be liable for damages (including costs and attorneys’ fees) if you materially misrepresent that a product or activity is infringing your copyrights. Thus, if you are not sure content located on or linked-to by the Website infringes your copyright, you should consider first contacting an attorney.

                                                                                        Please follow these steps to file a notice:

                                                                                        You must include the following:

                                                                                        A physical or electronic signature of the copyright owner or a person authorized to act on their behalf An identification of the copyright claimed to have been infringed A description of the nature and exact location of the content that you claim to infringe your copyright, in sufficient detail to permit Varsity Tutors to find and positively identify that content for example we require a link to the specific question (not just the name of the question) that contains the content and a description of which specific portion of the question – an image, a link, the text, etc – your complaint refers to Your name, address, telephone number and email address and A statement by you: (a) that you believe in good faith that the use of the content that you claim to infringe your copyright is not authorized by law, or by the copyright owner or such owner’s agent (b) that all of the information contained in your Infringement Notice is accurate, and (c) under penalty of perjury, that you are either the copyright owner or a person authorized to act on their behalf.

                                                                                        Send your complaint to our designated agent at:

                                                                                        Charles Cohn Varsity Tutors LLC
                                                                                        101 S. Hanley Rd, Suite 300
                                                                                        St. Louis, MO 63105

                                                                                        Vertebrae classification models - Validating classification models that use morphometrics to identify ancient salmonid (Oncorhynchus spp.) vertebrae to species

                                                                                        Using morphometric characteristics of modern salmonid (Oncorhynchus spp.) vertebrae, we have developed classification models to identify salmonid vertebrae to the species level with relatively low error rates. This is a study to validate the performance of our classification models on ancient salmonid specimens using analysis of ancient DNA. We have putatively identified a sample of ancient (ca. 1000 to 2900 ybp) vertebrae (from the Wenatchee River basin) to species with our models. Using molecular markers to identify the ancient vertebrae to species, we will be able to evaluate the performance of our models that use vertebral morphology for species identification. If identification methods that are based on vertebral morphology perform successfully, we will have a rapid, low cost, nondestructive method to identify ancient salmonid vertebrae. If applied to midden sites throughout the Columbia River basin, and potentially to other river systems draining into the Pacific Ocean, we will improve our understanding of historical anadromous salmonid occupancy and have a more complete picture of historical population and ESU structure. Additionally, the results of this work have the potential to make a significant contribution to inland and coastal anthropological/archaeological investigations. Collaborators include: Virginia Butler (Portland State University, Dept. of Anthropology), Harriet Huber (AFSC), and Dongya Yang (Simon Fraser University, Ancient DNA Laboratory).

                                                                                        Watch the video: ΝΩΤΙΑΙΟΣ ΜΥΕΛΟΣ (December 2022).