Name: GEOL 104 Dinosaurs: A Natural History Smithsonian Assignment I: Life on Land before the Dinosaurs, and the Dinosaurs Themselves! DUE: October 27 “Every man is a valuable member of society who by his observations, researches, and experiments procures knowledge for men.” -James Smithson (1765-1829), a British natural historian whose legacy of over $500,000 was given to the government of the United States of America for the creation of “an Establishment for the increase and diffusion of knowledge”: the Smithsonian Institution. The Smithsonian Institution’s National Museum of Natural History (NMNH) has one of the largest collections of dinosaur and other fossils in the world. The Smithsonian museums are free; hours for the NMNH are 10 am to 5:30 pm 7 days a week. You can take the Metro from the College Park Station to any of a number of stations near the Museum. The quickest route is the Green Line from the UMd-College Park Station to Archives/Navy Memorial: you don’t have to change trains, and the NMNH is just on the other side of the Archives Building. For this exercise you may wish to bring along the anatomy sheets handed out in class. You may work in teams and discuss your answers; however ALL WORK YOU TURN IN MUST BE YOUR OWN. (I have caught and reported a number of students in the past you have cheated by copying each other’s work: please don’t make me do that again…). To comply with University Senate regulations, please sign the following so that you may receive credit for this assignment. I pledge on my honor that I have not given or received any unauthorized assistance on this assignment Signature UID Date NOTE: Use your OWN OBSERVATIONS in order to answer the questions. This package works as sort of a self-guided tour. It will start in the Conquest of the Land exhibit, and end up in the Dinosaur Hall. 1Name: PART I – LIFE ON LAND BEFORE THE DINOSAURS For this exercise, you will probably find the anatomy sheets handed out in class (also available on the website) a useful guide in identifying the homologous bones in these different animals. On the first floor, find the exhibit called “Conquest of the Land” (also labeled “Fossil Plants” on some maps). These exhibits discuss the colonization of land by plants and early stegocephalians (“amphibians” in the old sense). Find the case labeled “Amphibians—The Vertebrates Take to Land”, and locate the model of the crossopterygian fish Eusthenopteron. Compare the front (pectroral) fin to the images below: 1) The front (pectoral) fin of Eusthenopteron more closely resembles fin [ (a) | (b) ] Find the mounted skeleton of Eryops, a large stegocephalian. 2) Based on the shape of its teeth, do you think that it ate fish and meat, or that it ate plants? 3) What evidence led to you to your answer in question 2? [Note also the skeleton of Pelosaurus laticeps, a possible “tadpole” of Eryops.] 2Name: In the center of this room is a set of fossils of the stegocephalian Buettneria perfecta that were found together. 4) Based on the text (hanging from the ceiling), what is the likely reason for the particular grouping and position of the bones? Head for the early “reptiles” (really “early amniotes”) exhibits: look for an Allosaurus foot in a glass cylinder to find your way. Below are cartoons of three major skull types found in amniotes. They differ by the patterns of the temporal fenestrae (the openings for jaw muscle attachments). Anapsid (no temporal fenestrae) Synapsid (infratemporal fenestra) Diapsid (supra- and infratemporal fenestrae Find the skeleton of Diadectes in the display case labeled ‘”Stem” Reptiles’”. This creature is very close to the base of Amniota: some paleontologists think that it is a true amniote, while others think that it lies just outside that group. 5) What skull type does Diadectes have? [ anapsid | synapsid | diapsid ] Extra Credit) Paleontologists agree that Diadectes wasn’t a flesh-eater. What feature(s) of the teeth suggests a non-meaty diet for this animal? 3Name: Find the exhibit labeled “The First Wave of Reptilian Diversity”, featuring the skeletons of Dimetrodon grandis, Edaphosaurus boanerges, and Cotylorhynchus romeri. In modern classifications, these animals would not be considered reptiles, although it is fair to say that they were part of the first wave of amniote diversity. Dimetrodon, with the largest skull, is probably the best one to look out for the next two questions. 6) These animals have the [ anapsid | synapsid | diapsid ] skull type. 7) These animals [ do | do not ] have an antorbital fenestra. Extra Credit) In which of these three animals are the teeth most differentiated in size and shape between the different parts of the jaws? [ Dimetrodon | Edaphosaurus | Cotylorhynchus ] The ancestral state for limb postures in tetrapods is sprawling (limbs oriented out to the sides); the derived state is parasagittal (limbs oriented downward). Indicate the limb posture of the following tetrapods: 8) Dimetrodon [ Sprawling | Parasagittal ] 9) Edaphosaurus [ Sprawling | Parasagittal ] 10) Diadectes [ Sprawling | Parasagittal ] 11) Cotyloryhnchus [ Sprawling | Parasagittal ] Find the exhibit labeled “Cynodont Flesh-Eaters”. On display are the skull of the large Cynognathus crateronotus and the much smaller skeleton of Thrinaxodon liorhinus. 12) These taxa have a [ anapsid | synapsid | diapsid ] skull type. The primitive condition for tetrapod teeth is undifferentiated (the same shaped teeth from the front of the snout to the back); the derived state is differentiated (specialized teeth in different parts of the jaws). 13) The jaws of the cynodonts show [ undifferentiated | differentiated ] teeth. Find the case labeled “Early Reptilian Plant-Eaters” (again, these are actually synapsids, not true reptiles). The particular type here are various dicynodonts. Find the large skull of Aulacephalodon baini. 14) How many teeth (total) are present in the skulls of these animals? 4Name: Move on to the exhibit un-creatively named “Non-Dinosaurs”. Find the skeleton of the Triassic reptile Trilophosaurus buettneri. 15) The limbs of Trilophosaurus are [ sprawling | parasagittal ]. Look behind you at the skeletons of dicynodonts, and back at Edaphosaurus, Dimetrodon, and Cotylorhynchus.