Paleo 419 Lab 8

Clade Saurischia Synapomorphies

Includes Sauropodomorpha and Theropoda

• pubis is directed anteriorly

• narial fossa is expanded in the anteroventral corner of the naris

• lacrimal overhangs the posterior or posterodorsal part of the antorbital fenestra

• distal end of the pubis is expanded relative to the shaft

Clade Sauropodomorpha (Clade Saurischia) Groups

Plateosauridae and Sauropoda (includes Diplodocoidea and Macronaria)

• first dinosaurs to exceed a ton in weight

• include the largest land animals

• Herbivorous

Clade Sauropodomorpha (Clade Saurischia) synapomorphies

• skull length less than 50% of the length of femur

• small, high-crowned teeth

• 10+ cervical vertebrae; mid and posterior cervicals are longer than the dorsal vertebrae

• at least 3 sacral and 25 pre-sacral vertebrae

• ungual 1 of manus and pes are greatly enlarged

• large obturator foramen in the pubis

• large anterior process of ilium

?

Diplodocus (Clade Sauropodomorpha, Clade Saurischia)

?

Brachiosaurus teeth (Clade Sauropodomorpha, Clade Saurischia)

What are these?

Gastroliths common in Clade Sauropodomorpha (Clade Saurischia)

Clade Theropoda (Clade Saurischia) synapomorphies

• obligate bipeds

• reduced overlap of dentary and postdentary bones in mandible

• intramandibular joint

• compact, narrow metatarsus

?

Herrerasaurus (Clade Theropoda, Clade Saurischia)

?

Eoraptor (Clade Theropoda, Clade Saurischia)

?

Eoraptor (Clade Theropoda, Clade Saurischia)

Superfamily Coelophysoidea (Clade Theropoda) traits

• long, narrow skulls that were lightened by very large fenestrae

• subnarial diastema

• premaxillary teeth that do not extend beneath the external naris

Family Dilophosauridae (Clade Theropoda) traits

• one of the first large carnivorous theropods

• slender bodies with a narrower skull

• premaxillary posterodorsal process contributing to a blade-like nasal crest

• antorbital fossa extending onto the lateroventral face of the nasal

• nasolacrimal crest

?

Ceratosaurus (Family Dilophosauridae, Clade Theropoda)

?

Coelophysis (Superfamily Coelophysoidea, Clade Theropoda)

?

Cryolophosaurus (Family Dilophosauridae, Clade Theropoda)

Clade Tetanurae (Clade Theropoda) synapomorphies

• closely related to birds

• maxillary fenestra

• maxillary teeth always anterior to orbit

• large manus

• manual digits 4 and 5 lost

• stiff posterior region of tails

Groups in Clade Tetanurae (Clade Theropoda)

• Megalosauroidea (including Spinosaurus)

• Allosauroidea (including Allosaurus, Carcharodontosaurus, Sinraptor, and Megaraptor)

• Coelurosauria

Superfamily Megalosauroidea (Clade Tetanurae, Clade Theropoda) traits

Includes spinosaurids

• semi-aquatic and fed largely on fish

• elongate, crocodile-like skulls

• External nares retracted further than any of other theropods

• Sails on backs

?

Megalosaurus (Superfamily Megalosauroidea, Clade Tetanurae)

A

Marshosaurus (Superfamily Megalosauroidea, Clade Tetanurae)

B

Megalosaurus (Superfamily Megalosauroidea, Clade Tetanurae)

C

Baryonyx (Superfamily Megalosauroidea, Clade Tetanurae)

?

Suchomimus (Superfamily Megalosauroidea, Clade Tetanurae)

?

Superfamily Megalosauroidea (Clade Tetanurae)

Superfamily Allosauroidea (Clade Tetanurae) traits

• pneumatic nasal recesses

• long axis of naris more than half the length of the long axis of the orbit

• lateral surface of nasal participates in edge of antorbital fossa

• prefrontal is excluded from lateral margin of orbit in lateral view

• supraorbital notch between prefrontal and postorbital

• Large orbits

• Crests cranial ornamentation

What bone forms the crest in Monolophosaurus and Dilophosaurus

Nasal bones

?

Acrocanthosaurus (Carcharodontosaurids, Superfamily Allosauroidea)

?

Acrocanthosaurus (Carcharodontosaurids, Superfamily Allosauroidea)

?

Allosaurus (Allosauridae, Superfamily Allosauroidea)

?

Saurophaganax (Allosauridae, Superfamily Allosauroidea)

?

Sinraptor (Superfamily Allosauroidea, Clade Tetanurae)

Clade Coelurosauria (Clade Tetanurae) synapomorphies

Includes birds

• ischium 2/3 the length of the pubis

• triangular obturator process on ischium

• loss of ischial foot

• elongate prezygapophyses on mid to posterior caudal vertebrae

• metacarpal III smaller than Metacarpal II

Family Compsognathidae (Clade Coelurosauria, Clade Tetanurae) traits

Includes Compsognathus and Archaeopteryx

• fan-shaped dorsal spines

• more than 60 caudal vertebrae

• manual ungual of digit I more than 2/3 length of radius

?

Compsognathus (Family Compsognathidae, Clade Coelurosauria)

?

Sinosauropteryx (Family Compsognathidae, Clade Coelurosauria)

Superfamily Tyrannosauroidea (Clade Coelurosauria, Clade Tetanurae) traits

• Tall skulls

• weakly heterodont teeth

• elongate metatarsus (arctometatarsalian pes in derived tyrannosaurids)

• D-shaped premaxillary teeth in cross-sectional view

• body of premaxilla taller than long anteroposteriorly

?

Gorgosaurus (Superfamily Tyrannosauroidea, Clade Coelurosauria)

?

Tyrannosaurus arm (Superfamily Tyrannosauroidea, Clade Coelurosauria)

?

Superfamily Tyrannosauroidea (Clade Coelurosauria)

?

Nanotyrannus (Superfamily Tyrannosauroidea, Clade Coelurosauria)

?

Tarposaurus (Superfamily Tyrannosauroidea, Clade Coelurosauria)

?

Albertosaurus (Superfamily Tyrannosauroidea, Clade Coelurosauria)