|GEOL 104 Dinosaurs: A Natural History
Anatomy and Taxonomy Assignment
DUE: Mon. Sept. 27
Part I. Comparative Anatomy
Below is the skull of the small primitive plant-eating dinosaur Thecodontosaurus antiquus.
For 1-6: Using Appendix Figure 4 (p. 265) in the textbook, the handout from class, and the website, label the bones indicated on the skull above by the thin arrows. There are 6 bones to label. Write the name of the bone at the end of the thin arrow.
For 7-10, you will identify the four openings in the skull indicated by the thick bold arrows. Use the information below to recognize the different openings:
Antorbital fenestra: anterior to the orbit, posterior to the naris, surrounded by the maxilla, lacrimal, and nasal bones
Infratemporal fenestra: posterior to the orbit, ventral to the supratemporal fenestra, surrounded by the jugal, quadratojugal, squamosal, and postorbital bones
Mandibular fenestra: within the mandible (lower jaw), surrounded on the anterior end by the dentary and the posterior end by the surangular and angular bones
Supratemporal fenestra: posterior to the orbit, dorsal to the infratemporal fenestra, surrounded by the squamosal, postorbital, frontal, and parietal bones
In the skeleton above, identify by name or number the following bones (the Appendix of the book and the handouts will help with this):
11) A Cervical (neck) Vertebra 12) A Dorsal (back) Vertebra 13) A Caudal (tail) Vertebra
14) A Rib 15) Scapula 16) Coracoid 17) Ilium 18) Ischium 19) Pubis
20) Humerus 21) Femur 22) Tibia 23) Fibula 24) Ulna
25) A Metacarpal 26) A Metatarsal 27) Chevron 28) Acetabulum
Extra Credit) The dinosaur above is [ bipedal | quadrupedal ]. (Circle the correct answer)
Part II. Taxonomy
1) Allosaurus fragilis was named in 1877; Creosaurus atrox was named in 1878. If later studies indicate that these are two different species within the same genus, what would be the name of these two species?
2) If, instead, Allosaurus fragilis and Creosaurus atrox are discovered to be different specimens of the same species, what would be the name of this species?
Extra Credit. What is the ONLY proper abbreviation of Tyrannosaurus rex?
Part III. Systematics
Below is a cladogram showing the interrelationship of various dinosaurs and related forms.
1) What is the closest relative to Hylaeosaurus on this cladogram?
2) What is the closest relative to Iguanodon on this cladogram?
3) The clade Ornithischia is defined as Iguanodon and all taxa sharing a more recent common ancestor with Iguanodon than with Megalosaurus. List all the taxa on this cladogram which are members of Ornithischia.
4) Name a shared derived character of Ornithischia as listed on the cladogram, with extra credit for a second.
5) The clade Saurischia is defined as Megalosaurus and all taxa sharing a more recent common ancestor with Megalosaurus than with Iguanodon. List all the taxa on this cladogram which are members of Saurischia.
6) What is the closest relative to the clade comprised of Iguanodon + Hylaeosaurus on this cladogram?
7) Dinosauria is defined as the most recent common ancestor of Iguanodon and Megalosaurus and all of its descendants. According to the cladogram above, is Lagerpeton a dinosaur? [ Yes | No ]
8) Is Thecodontosaurus a dinosaur? [ Yes | No ]
Below is a cladogram and data matrix of the ostrich dinosaurs (Ornithomimosauria). In the data matrix, a “0” indicates that the derived feature (mentioned on the left) is absent; “1” indicates that the derived feature is present; and “?” means that the feature cannot be evaluated (in these cases, that part of the body isn’t known for the genus). For example, Ornithomimus is toothless, has a long metacarpal I, and a pinched metatarsal III. Harpymimus shows the primitive (ancestral) condition: it has teeth, a short metacarpal I, and an unpinched metatarsal III.
9) Based on the cladogram above, which dinosaur is characterized by a toothed jaw and a long metacarpal I?
10) The skull of Anserimimus is not known at present. Based on the data available, do you predict that this dinosaur was toothed or toothless? Justify your answer.
Extra Credit) Only the front end of Pelecanimimus is known at present. Based on the information above, is it possible to predict if it had a pinched metatarsal III or not? Explain your answer.