Vertebrate paleontology

• 
• amniota
• synapsida
• eureptilia
• anapsida
• diapsida
• neodiapsida

• Can lay eggs out of water
• ancestors of all subsequent tetrapods groups (Permian to present); Reptiles, birds and mammals
• Traditionally used Class Reptilia=paraphyletic becasue it excludes birds and mammals which are descendants of these earlier forms
• Early forms small and lizard-like
• Ate small prey (insects and worms)

appeared in mid Carboniferous, small bodied, small headed

• Divided into 5 regions
• 1. Cheek -10 bones
•     Premaxilla and maxilla bear teeth
• 2. Skull table - three paired bones
•     Parietal foramen
• 3. Palate - four paired bones and one unpaired
•     Early animals have palatal teeth-lost later
• 4. Occiput - six paired bones and one unpaired
•     Contain bones that support the innter ear semicircular canals
• 5. Lower jaw - five paired bones
• Extensive dermal roof bones
• No temporal notch or eardrum

• Lightly built
• vertebrae= large pleurocentra with small intercentra between
• modified C1 and C2 allow head to turn on neck
• Atlas derived from six elemnts
• Axis - fused plurocentrum and neural arch; small anterior intercentrum
• dorsals
• sacrals
• caudals

accommodates ball-and-socket of skull occipital condyles to allow rotational movements

• allows "no" movement
• subsequent 2-4 cervicals similar but with smaller neural arches; short ribs

bear long ribs; form rib cage

• Fishes have trunk and caudal vertebrae
• Other vertebrates, vertebrae differentiated into up to five types

• large fused scapulocoracoid
• -scabula and two coracoids
• -screw shaped glenoid fossa for humearl head
• -Cleithrum and clavicle reduced to thin bone strips anterior to scapulocoracoid
• -interclavical long and "T" shaped

• Short arm
• Long and slender hand with the same wrist bones as in Eryops
• Phalangeal formula=2,3,4,5,3

Narrow ilium and pubis and ischium beneath

• Longer than hand
• More slender ankle bones
• Tibiale, centrale and intermedium fused to form astragalus
• Fibulare enlarges to become calcaneum
• Foot phalangeal formula=2,3,4,5,3 (same number of digits for hand and foot

abdominal ribs protect belly region

• Light skulls and small sharp teeth for feeding on invertebrates (insects and millipedes)
• Pterygoid muscles assist jaw adductors to increase closing strength
• Stapes heavy and limited to hearing low frequency sounds
• Early amniotes lack otic notch and therefore, no tympanum
• Light animals fossilized in tree trunks!

• ex: small animals fell into holes left by rotted tree trunks and could not extricate themselves, so became well preserved
• A sad event for each poor little critter, but good for paleontologists!

earliest identified amniote

• Semipermeable shells
• Contains sufficient fluid and food for embryonic development
• Not laid in water; can be laid on dry land
• No aquatic larval stage of life
• Requires internal fertilization
• complex egg type probably evolved only once

• Chorion surrounds embryo and yolk sac
• Amnion surrounds embryo with water
• Allantois - sac for respiration and waste storage

• 
• Anapsid - no fenestrae
• Synapsid - one fenestrae
• Diapsid - two fenestrae, one above the other
• Euryapsid - one upper fenestra

changes to accommodate different numbers of fenestrae and positions

• small, Permian anapsids
• fully aquatic, up to 1m long
• slender teeth work as strainers for small prey

• small, active, insectivorous as are modern lizards
• Permian anapsid

• Bolosaurids - 5-6 genera, lower Permian
• First bipedal tetrapod
• Herbivorous, with occluding (interlocking) teeth

• locality, found in 1930s in East Germany.
• New tetrapod locality became known after fall of Berlin wall and East and West Germany reunited and their scientists gained  contact with the rest of the world.
• Many complete, delicate speciments "Death assemblages"

• Parieosaurus-heavily built
• A Procolophonid
• Herbivores
• sister groups of turtles
• Heart shaped heads with multiple rows of peg-like teeth - ate inverts or tough plants - tooth replacement to outside jaws

• Areoscelids-early diapsids
• Both aquatic and terrestrial forms
• had suborbital fenestrae
• sharp teeth
• ate insects

• Late Permian diapsids
• Coelurosauravus - glider as is living Draco
• Protosaurus - earliest archosauromorph
• Youngina - lizard-like insectivore and carnivore

• Coelurosauravus restoration
• doing what comes naturally

• Ophiacodonts
• 6-7 genera
• Mid-Carbinferous-Early Permian
• Archaeothyris-poorly known (top)
• Ophiacodon-largest anmiote so far 1.5m in length, large headed carnivore, eating fish and other tetrapods

Ophiacodon eating lunch

• Eothrysis (top left)
• Cotylorhynchus- Herbivore, very small skull, caseids-herbivorous pelycosaurs (sail backs) (top right)
• Varanops- usually long tooth row (bottom)

• edaphosaurus- one of two groups of sail-backed reptiles
• Herbivorous with beg-like teeth, deep jaw, head relatively small for body size, jaw movement anteroposterior (propralinal) and large battery of crusing palatal teeth
• pelycosaurs

• Dimetrodon-large, carnivorous pleycosaur (sphenacodontid)
• Upper Carboniferous and Lower Permian
• (Texas and Europe)
• Large-up to 3m long
• "sail" richly vascularized-probably for thermoregulation
• One of the best known spenacodontids
• pelycosaur

• Early therapsids
• Both herbivorous and carnivorous
• Identify anatomical characters that correlate with feeding habits

• Moschops-a herbivorous dinocephalian
• probably head-butted as do mountain sheep
• Identify anatomical characters that account for ability to perform this kind of behavior
• What does head butting reveal about overall life habits of the animal?

• Dicynodonts-
• dominant herbivores of late Permian
• could also be carnivorous
• Medium sized
• Died out mostly in Permian mass extinctions
• Surviving lineages into Triassic became as long as 3m; ecologically similar to present browsing mammals
• some dicynodonts lived in burrows, and could have died in floods
• burrows indicate life habits to this level of precision
• could chew
• had a beak, and probably used like turtles for cropping plants

• Gorgonopsidians showing off (dicynodont)
• dominant late Permian carnivores

• joints allow snout to lift or bend down
• changes angle at which teeth engage prey to prevent it squirting out of mouth from teeth at wrong angle to grasp it

• Anapsids (no temporal openings) -all muscles attach deep to dermatocranial elements-neurocranium to lower jaw
• Therapsids with temporal openings-jaw muscles shift to edges of openings, form initial zygomatic arch
• Jaw muscles move onto dermatocranial surface in therapsids and modern mammals

• 
• 3 kinds, named depending on where joint is and what parts move

• Posterior skull bones emarginated for muscle origin
• Trend increases through time.

• Sphenodon-two temporal fenestrae
• living diapsid

diapsids with lower border of lower opening missing, increasing cranial kinesis

• analysis of movement of parts of skull of lizard with a mesokinetic joint
• changes angle of closure of teeth
• allows for better grasp of prey by improving angle at which teeth hold prey
• 

• Chameleon uses the tongue to capture prey
• supported by large hyoid apparatus (which branchial arch derivative?)
• elongate lingual process at bottom

• snake skull biomechanics, water moccasin
• moveable bones are in color
• mechanical model of machine that allows kinesis in the anima

• Alligator skull with composite elements
• Lacks kinesis-secondary loss
• Kinetic-inertial feeding mechanism instead

bird skulls have kinesis also because they are light and bones bend, even though they rae fused in the adult

• cranial kinesis in a crow
• nasifrontal hinge allows bill to flex upward
• sliding crank mechanism model
• range of movement and gape is increased by cranial kinesis-sliding of joint allows jaw to open farther

Rhynochokinesis- Additional flexibility allowed by tips of beak;they can open without entire beak opening

• Paleognathous palate of ostrich
• Primitive pattern of palatal bone arrangement
• Compare bone patterns to those of other birds and reptilian ancestors

• Radiation of therapsids
• They continue synapsid line and have great body form diversity (and some are really cute!)

• Chondrocranium (blue) supports internal structures
• Jointed by splanchnocranium (yellow)
• These elements give rise to-
• Epipterygoid
• Articular
• Quadrate
• Hyomandibula
• Hyoid apparatus
• Dermatocranium encases most of chondrocranium

• amnoita-eggs which survive on land and nourish embryos with membranes
• Two major lineages-
• sauropsida
• synapsida
• Diverged by Carboniferous or earlier

• birds, dinosaurs, modern reptiles and Mesozoic reptiles
• two groups-
• Parareptilia
• Eureptilia

• Monophyletic
• Therapsids, modern mammals and extinct forms

• Amniote skull types used to be used in classification, but no longer.  Now, functional types only.
• Traditional means of dividing groups by skull opening pattern
• No longer used phylogenetically

• Stem amniotes, diadectomorphs
• Late Carboniferous
• Related to Seymouriomorphs and amphibia
• Perhaps belong with anthracosaurs and other late non-amniotes
• also called Cotylosauria
• what we believe all other amniotes came from