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GEOL 104 Dinosaurs: A Natural History
Smithsonian Assignment II: Dinosaurs, Mesozoic Marine Life, and the Cenozoic Era (but mostly dinosaurs)
DUE: November 22
The Smithsonian Institution’s National Museum of Natural History (NMNH) has one of the largest collections of dinosaur and other fossils in the world. This exercise will concentrate on the wonderful dinosaur fossils on exhibit.
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 dinosaur cladograms handed out in class. You may work in teams and discuss your answers; however ALL WORK YOU TURN IN MUST BE YOUR OWN. 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 Date

This package works as sort of a self-guided tour. It will start you at one end of the Dinosaur Hall, then lead you through that Hall (including the upstairs), then through the Mesozoic section of the Life in the Ancient Seas Hall, and finally take you into the Hall of Fossil Mammals and Hall of Ice Age Mammals to get a glimpse at life after the Age of the Dinosaurs.
Some things to keep in mind:

  • Remember proper handwritten taxonomic grammar:

    • Genera have one-word, capitalized, and underlined names:

      • Examples: Giganotosaurus Brachiosaurus

    • Species have two-word, underlined names; the first part of the name (which is the same as the genus name) is capitalized, but the second part of the name is not:

      • Examples: Giganotosaurus carolinii Brachiosaurus altithorax

  • When given a choice of items in bracket, circle the appropriate answer.


We’ll start with the king! Enter the main Dinosaur Hall, and go up the short stack of steps to the “main” level of the hall. Find the Tyrannosaurus rex skeleton (shouldn’t be too hard…). Gaze at its majesty for a bit. Incidentally, Dr. Holtz worked on the (admittedly limited) text associated with this exhibit. Now, answer the following questions:

1) Which are larger? [ Its largest manual unguals | Its longest teeth ]

2) How many digits does it have per manus?

3) How many digits does it have per pes?

Find the metatarsus (the long bones of the foot between the ankle and the toes). Compare the length of the metatarsus as a whole to the length of the femur.

4) The metatarsus is [ less than ¼ the femur length | about ½ the femur length | as long as the femur ].

The Tyrannosaurus is facing its contemporary, the ceratopsid Triceratops. The Triceratops exhibit has been greatly expanded and updated in recent years. Go back down the steps into the alcove of the Triceratops exhibit. Read the text and view some of the videos.

5) The original skeleton has been removed from display, and a plastic copy has been used to replace it. What was the main reason for this switch?

6) The technology used to make the new cast (laser scanning, computer aided design, rapid prototyping, and such) is pretty interesting. What flaws of the old mount was the Smithsonian team able to correct by using this new technology? (Give at least two flaws, with extra credit for a third).

Now go up the steps and look at “Hatcher”, the Smithsonian’s new Triceratops mount.

7) In Triceratops the metatarsus is [ less than ¼ the femur length | about ½ the femur length | as long as the femur ].

Continue on through the ceratopsian and pachycephalosaur exhibits.

8) There are specimens of a couple of centrosaurines represented by fossils here. Compare the skull of Centrosaurus with that of Triceratops. Which of the two is larger?

9) What centrosaurine genus (formerly considered its own genus and species, Brachyceratops montanensis) is represented by a juvenile individual?
Primitive (non-ceratopsid) ceratopsians are represented by three skulls: Protoceratops, Bagaceratops, and Psittacosaurus.

10) In which of these primitive ceratopsians is the frill the longest, in terms of relative size to the rest of the skull?

11) Several pachycephalosaurs are also on display here. What is the full species name of the largest pachycephalosaur on exhibit?

Thescelosaurus neglectus and Heterodontosaurus tucki are two ornithopod dinosaurs. Both mounted on the wall near the Marginocephalia exhibit.

12) These two dinosaurs are [ bipedal | quadrupedal ].

13) [ Thescelosaurus | Heterodontosaurus | both ] could have been on the diet of Tyrannosaurus rex.

14) [ Thescelosaurus | Heterodontosaurus ] is the older of the two.

Move along to the hadrosaurids, much larger ornithopods.

15) The hind end of Corythosaurus casuarius is displayed. What non-bony feature is preserved here that you don’t see preserved on the rest of the skeletons in this hall?

Further down, the complete skulls of an adult hadrosaurine and a juvenile lambeosaurine are on display.

Examine the skull of the hadrosaurine Edmontosaurus annectens, one of the “duckbill-iest” of the duckbills.

16) The teeth in Edmontosaurus are [ restricted to the anterior half of the snout |

distributed evenly throughout the jaws | restricted to the posterior half of the snout ].
17) Adults of Corythosaurus have a tall crest over the top of the skull. Does the skull of the juvenile Corythosaurus show this as well?
Turn around, and find the eggs of the deinonychosaur Troodon (the only raptor fossils on display here!) and the baby Maiasaura skeleton. Maiasaura is a hadrosaurine hadrosaurid. (These Cretaceous fossils are a bit out of place, since all the other dinosaurs in this central island are from the Late Jurassic Morrison Formation).

18) In terms of the length of the snout vs. the entire length of the skull, the baby Maiasaura is more similar to

[ Heterodontosaurus (see questions 12-14) | Edmontosaurus ].
Turn back around to the wall, and pass the cast of the Tyrannosaurus rex skull. Examine the skeleton of Ceratosaurus nasicornis. This is the type specimen (the original one to which the name was assigned). New research indicates that it wasn’t fully grown when it died.

19) How many fingers does it have on each hand?

20) This dinosaur was a [ carnivore | herbivore ].
Turn around and face the main island. As mentioned above, all the dinosaurs in the central island (other than the eggs and baby fossils) are from the Late Jurassic Morrison Formation of western North America (from which Ceratosaurus also came). In front of you, on the floor of that display, is a dinosaur mounted in “death position” (i.e., the way it looked when it was found in the rocks), rather than “life position” (standing upright).

21) What dinosaur species is shown in death position at this point?

(Incidentally, note the bony armor knobs around the cervical vertebrae).

The central island is dominated by Diplodocus, a very long sauropod.

22) Find the distal caudals (the tail tip) of Diplodocus. Circle whichever of the following is a better description of the anatomy of these bones:

  1. Very complex, with large transverse processes and tall neural spines

  2. Very simple cylinders, with no transverse processes and no neural spines

23) The fore- and hindlimb bones of this dinosaur are very straight (not very flexed at the joints). Why might sauropods have very straight limbs?

24) Move to the front end of the animal, and look up at the Diplodocus head. Even without rearing, it is still pretty tall! If you thought that it couldn’t rise up any higher than shown, what range of plants might it be able to eat:

A. Herbs (less than 30 cm (1 foot) high) only.

B. Herbs and Bushes (about 1 m (3 feet) high) only.

C. Herbs, Bushes, and Trees.

D. Trees only: incapable of lowering its head.
Continue along the central island. Move down the rail, and find a pair of sauropod skulls. One is a macronarian, and one is a diplodocoid. Identify what representative from each group is shown:

25) Macronarian:

26) Diplodocoid:
Extra Credit) Which one has thicker teeth?
27) The Camarasaurus lentus skeleton directly beneath the two sauropod skulls from the previous question is in

[ life | death ] position.

From this position you can see skeletons of three of the most common herbivorous dinosaurs of the Morrison Formation: Camarasaurus, Diplodocus, and (down the path) Stegosaurus. (The fourth most common Morrison herbivorous dinosaurs, the ornithopod Camptosaurus dispar, is on display as a juvenile, but the adult is currently taken down for repairs). In nature, animals with similar diets divide up the ecosystem so that they reduce direct competition with each other. One way of doing this is by feeding at different heights.

28) Arrange these three dinosaurs in relative feeding height (assume that they did not rear up):

Tallest feeder:

Middle feeder:

Lowest feeder:
Continue along, and find the recently remounted skeleton of Stegosaurus.

29) How many pairs of spikes in the Stegosaurus thagomizer?

30) The many little osteoderms (not the plates or spikes) protect what part of this dinosaur?
Continue along, and stop at the Allosaurus skeleton.

31) Which are larger? [ Its largest manual unguals | Its longest teeth ].

32) How many digits per manus does it have?

33) How many digits per pes does it have?

Incidentally, this particular individual had a tough life. Its left scapula was broken and rehealed improperly. The real ribs of this specimen (which are in the collections rather than on display: what are on display are plaster ones) are damaged along the left side, and the left dentary was so damaged and rehealed in such an unusual way that it was thought to be from a whole new dinosaur (named “Labrosaurus”). All this points to the Allosaurus having suffered a massive blow along one side that broke bones from the jaw tip through the torso.

34) What evidence is there that this blow was not fatal?

Extra Credit) Which of the Morrison herbivores on display would have been the most likely candidate for causing that blow, and why?

Behind you are the stairs to the upper deck of the Dinosaur Hall. Before walking up the stairs, examine the small display of Mesozoic mammals and insects.

35) The tiny Mesozoic mammal fossils are all represented by what general part of the body?

Now head up the stairs. From the upper deck of the Dinosaur Hall, find the overlook and look down at the central island. Look at the dinosaurs from above.

36) Note that the Allosaurus is skinnier in the torso and hips than Stegosaurus or Diplodocus. What advantage might herbivores get from having a wider body?

Turn around and look at the pterosaur exhibit.

Overhead is a reconstruction of the giant pterosaur Queztalcoatlus. Find the cast of an actual bone of this pterosaur.

37) As precisely as possible, which bone is represented by a cast? (I.e., don’t just say “arm bone”!! You are getting college credit for this…)

38) Does this bone have a small muscle attachment surface, or a large one?
Move around to the main pterosaur displays. Take a look at the Pteranodon skeletons (either the mounted complete skeleton, or the larger isolated wing).

39) The distal part of the pterosaur wing is comprised of digit [ I | II | III | IV | V | VI | VII ].

Move to the other side of this panel, and find the exhibit on early birds. There are casts of the first two skeletons of Archaeopteryx lithographica on display.

40) How many digits per manus does Archaeopteryx have?

41) How many digits per pes does Archaeopteryx have?
Head over to the ramp, and walk up it a bit. Find the exhibit sign labeled “What’s for Dinner?” that describes the two wall-mounted specimens on the opposite wall. One is the hadrosaurine Edmontosaurus (in life position), a contemporary of Tyrannosaurus and Triceratops. The other (in death position, although tilted so that what was once the upper surface is facing you) is the tyrannosaurid Albertosaurus (actually it’s Gorgosaurus by current taxonomy), a dinosaur from about 10 million years earlier than Edmontosaurus. In fact, it was a contemporary of the centrosaurine Centrosaurus that you saw in question 7.
Edmontosaurus, Triceratops, and Tyrannosaurus are the three most common large dinosaurs of the Hell Creek Formation (the youngest rocks from the Age of Dinosaurs in North America). Take a look at them together from your vantage point (you won’t be able to see all of Triceratops, but you can see enough).
42) Which herbivore would have had a higher feeding range? [ Edmontosaurus | Triceratops ]
43) Which of the two tyrannosaurids is larger? [ Albertosaurus | Tyrannosaurus ]
The directions on the next page will direct you to the next section of this project


From the “What’s for Dinner?” plaque, head back downstairs, past the Morrison Formation island, down the small stairs between Tyrannosaurus and Triceratops, and take a right turn into the Hall of Ancient Life in the Seas. Once there, take a right (that is, go underneath the sign labeled “Act Two – The Mesozoic Era”). This hall documents marine vertebrate, invertebrate, and plant life throughout the last 544 million years with fossils, a great mural, and some life restoration models hanging about. The particular section you are in contains exhibits on the marine life of the Age of Dinosaurs.
Find the Mesozoic marine reptiles. These are mounted in front of or directly below the mural (and a few are in glass cases along the rail). In the list below, list a genus of each of the following groups that is on display:

44) A marine bird: 45) A nothosaur:

46) A turtle: 47) An ichthyosaur:

48) A plesiosaur: 49) A mosasaur:

50) A placodont: 51) A marine “crocodilian” (actually a non-crocodilian

crocodyliform in modern taxonomy):

The seas of the Mesozoic, like those of today, had diverse types of “shellfish” (invertebrates). Many examples are on display: some along the wall with the main mural, others in the center “island”, and still others on their own display labeled “Taking Cover” on the wall opposite from the main mural.

In the center island, facing the marine reptiles, is an exhibit about ammonites (extinct relatives of the modern octopi, squids, and nautili.)

52) Most of the ammonite species on display have [ straight | coiled ] shells.
Move down to the display of rudists, near the skeleton of Tylosaurus proriger. These are a diverse group of extinct clams, but they don’t look very clam-like.

53) According to the display, what sort of environment did rudists live in (and, indeed, form)?

Before leaving this hall, stop by the “Taking Cover” exhibit, and admire the enormous ammonite!


Now you’ll be heading to the fossil mammal halls. Move down the Hall of Ancient Life in the Seas into the next section (“Act Three – The Cenozoic Era”), and take a right up the steps labeled “Reptiles: Masters of the Land”. On the wall opposite those steps is a small exhibit on the Cretaceous-Tertiary impact and extinction. This exhibit includes a real deep-sea drilling core that actually contains the stratigraphic boundary from the Cretaceous Period to the Tertiary Period.

The display shows electron micrographs of the microfossils and other features found in this core. In particular, it shows the foraminifera (single-celled organisms with a calcareous shell) from above and below the impact layer.

54) According to this display, the foraminifera before the impact are best described as:

55) In contrast, the foraminferan after the impact are:
56) What unusual sort of geologic microscopic features did they find in the impact layer itself?

From this Cretaceous-Tertiary exhibit, turn left. Turn right (the only option), and then turn left again. You should be facing the entrance to the Hall of Fossil Mammals, with a sign labeled “Mammals in the Limelight”.

Pass the wonderful mounted skeleton of the ancient horse Hyracotherium vasacciensis, and head over to the start of the hall, past the “Plants in the Age of Mammals” display, to a glass case display of Mesozoic mammals. In general, as you follow the Hall of Fossil Mammals along you proceed upwards in time, tracing the history of North American mammals, other animals, and their environments through the Cenozoic Era. Each exhibit is organized by Epochs. Cenozoic Epoch names are different from those in the rest of geologic time: instead of being in the form “Late Jurassic Epoch” or “Early Permian Epoch”, each is given a unique name. From oldest to youngest, they are the Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, and Holocene (or Recent). The last two Epochs are part of the Quaternary Period, and have a hall of their own (the Hall of Ice Age Mammals). The rest are the Tertiary Period, and represent the exhibits in the main Hall of Fossil Mammals.

Compare the actual fossils (not the enlarged white models) of Mesozoic mammals with those of the Paleocene mammals.

57) Does there seem to be a size change from the Mesozoic to the Paleocene? If so, what change occurred?
The rest of the Tertiary is organized with a series of paintings in the back and the actual fossils and casts of fossils arrayed in front. Start with the Eocene exhibit.

58) In the glass cases are many specimens from the Green River Shale, a famous fossil locality. List three distinct types of organisms other than mammals that represented in these fossils:

59) The biggest animal in the main Eocene display is Uintatherium, a horned mammal. Uintatherium was a

[ bipedal carnivore | quadrupedal carnivore | bipedal herbivore | quadrupedal herbivore ].

60) Continue along the Eocene display. Rank the following animals in size (by “Largest”, “Medium”, and “Smallest”):

Diatryma (a bird):

Smilodectes (a primate):

Hyrachyus (a rhinoceros-relative):

Move on to the “Oligocene” Epoch exhibit (which are actually mostly latest Eocene Epoch mammals, by more recent geologic time studies).

61) What is the species (two word, italicized name!) of the largest animal represented by fossils in this display?
Extra Credit) There are a couple fossils of a group of reptiles that was common at this time on display. What sort of reptile are they?

Head on over to the Miocene Epoch exhibit.

62) Moropus is a very peculiar herbivorous mammal, closely related to modern horses, rhinos, and tapirs. Are its manual and pedal unguals more like hooves, or are they more like claws?

Stop over at the evolution of the horse exhibit “Evolution: Browsers to Grazers”. (Incidentally, the Smithsonian has an excellent collection of fossil horses).

63) Over the history of equids (horses) many aspects of their anatomy change. List at least two major different trends in horse evolution, with extra credit for a third trend.

Look at the Late Miocene-Early Pliocene Epoch display. The largest mammal here is the proboscideans (elephant relative) Stegomastodon.

64) Which of the following herbivorous dinosaur from the Dinosaur Hall was closest to Stegomastodon in overall size? [ Heterodontosaurus | Triceratops | Diplodocus ]
65) What evidence can you see that the rhinoceratoid Teleoceras fossiger was not a fast running animal?

Move into the Hall of Ice Age Mammals. As you enter, there is an exhibit of some odd mammals off to your left.

69) What species (i.e., two word, italicized name!) of giant ground sloth (two specimens are show) is exhibited?
Extra Credit) What was its diet?
70) Just like dinosaurs produced the ankylosaurs, so to the mammals produced their own heavily armored forms: the glyptodonts. On display is Glyptotherium arizonae. What is this animal’s likely diet?
71) To what modern animals (also on display) are Glyptotherium and other glyptodonts most closely related?

Turn around, and look at the fossils from Rancho La Brea (the famous La Brea Tar Pits) in the exhibit “Fossils and Tar Pits”. There are two species of carnivorous mammal here, threatening the ground sloth Paramylodon.

Give the species name for carnivorous mammals on display:

72) Dire wolf:

73) Sabre-toothed cat:
74) How do these Ice Age predators compare in size to Tyrannosaurus rex?
75) What is the species of giant carnivorous bird on display here?

Extra Credit) According to the display, why might so many carnivorous animals be found in the tar pits?

Further down in the Ice Age Mammal Hall are fossils of northern mammals. The two largest of these shown here are Mammuthus primegenius (the wooly mammoth) and Mammut americanum (the mastodon).

76) To which modern animals are these two most closely related?

Find the “mummy” of the extinct bison Bison crassicornus on display.

77) In dinosaur “mummies” the actual skin is not preserved, only the impression of the skin. Is the actual skin of this bison preserved? If so, how is that possible?

The animals in the main section of this hall were living in North America when humans first entered the continent 13,000 years ago (in some cases, they actually arrived at the same time). Indicate with an “X” which of the following species are now extinct:

78) Mammuthus primigenius: 79) Paramylodon harlani:

80) Teratornis merriami: 81) Alces alces:

82) Canis dirus: 83) Gulo gulo:

84) Smilodon californicus: 85) Cervalces alaskensis:
That’s it for this trip! While you are in the museum, use your time to examine some of the other exhibits.

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