AY Honors/Dinosaurs/Answer Key

1. What does the term dinosaur mean? Who used that term for the first time?

The word Dinosaur is a Latinized combination of the Greek roots “deinos” [terrible] and “sauros” [lizard] - so the word means Terrible Lizard. Sir Richard Owen, a British anatomist and taxonomist, coined the term in the early 1840s after determining that a set of fossil bones he studied, including those of Iguanodon and Megalosaurus, were not lizards, but something uniquely different.

There are several common characteristics of dinosaurs that separate them from other reptiles. Dinosaurs are terrestrial, have an upright posture (as opposed to most reptiles with offset limbs), a strong knee and ankle joint, and were diapsids (have two openings in the skull behind the eyes) with an additional hole on each side of the skull in front of the eyes (the antorbital fenestrae) and a hole on each side of the lower jaw (the mandibular fenestrae).

2. Discuss how scientists figure out what live dinosaurs may have looked like, considering that they may have had only a small number of bones / evidence to base their reasoning on.

One of the first steps in dinosaur reconstruction is comparative anatomy. Because bones often have analogous features, functions and articulation, paleontologists can make a first set of assumptions about the size, shape and gait of the dinosaur, even with only a small number of bones. Close investigation of bones can reveal signs of muscle attachment, which can further give shape to the dinosaur. Paleontologists also use comparative anatomy to see basic forms of animals in similar environments, using clues from the rock and other fossils around the dinosaur bones to infer a particular ecosystem, and looking at modern animals that live in similar ecosystems for potential models. In some cases, impressions of skin and feathers can offer some clues as to the external appearance. Although there is no fossilization of color, paleontologists can draw some inferences from patterns and colors in modern animals that live in similar ecosystems or have similar lifestyles.

3. Explain or discuss the following within a group or to an instructor.

a. Why is the Tyrannosaurus Rex considered to have been the king of the dinosaurs?

The Tyrannosaurus Rex was the top predator/consumer in its environment. Just as the Lion is the “King” in its modern environment, so too the T-Rex and its likes were “King” species. The T-Rex was particularly notable for its very large head/jaws which suggest significant biting power, and its large teeth.

b. What other dinosaurs are also considered dominate “king” species?

Other Tyrannosaurs are considered “King” species, such as the Albertosaurus and Tarbosaurus. The various Carnosaurs, such as Allosaurus and Acrocanthosaurus (whose tracks can be seen in Texas), were also “King” species in their environments.

c. Why did dinosaurs lay eggs.

Many modern reptiles are egg layers, as are modern birds, which are considered related to the dinosaurs. Fossilized dinosaur eggs have been found, offering evidence that at least some of the dinosaurs were egg layers.

d. What types of skin did dinosaurs likely have? Give species examples of each.

Although much rarer than fossilized bones, skin prints from dinosaurs have also been found in the fossil record. Many prints highlight bumpy skin, small or large non-overlapping scales and in some species bony plates. Hadrosaurs have some of the best preservation of skin prints, showing non-overlapping bumpy scales, sometimes nearly hexagonal in shape. Dinosaurs like Stegosaurus had bony plates on their skin, possibly for protection, thermoregulation, sexual advertising or a combination of the three. The Ankylosaur had osteoderms - bony projections and plates - embedded its its skin that provided a complete armor coating.

e. What are the sauropodomorphs?

Dinosaurs are in general divided into two groups, the Ornithischians (“Bird-Hipped” dinosaurs, all herbivorous, including well-known kinds such as Triceratops, Stegosaurus, and Hadrosaur), and the Saurischians (“Lizard-Hipped” dinosaurs) which are divided into two main groups, the Theropods (“Beast-Footed” Dinosaurs, such as Tyrannosaurus Rex and Deinonychus) and the Sauropodomorphs (“Lizard-Foot Form” Dinosaurs), which include the largest of the land animals, such as Diplodocus, Seismosaurus and Apatasaurus.

f. In which two groups are they divided?

Sauropodomorphs are divided into two categories. The smaller prosauropods (“Before Lizard-Foot” Dinosaurs), were mostly herbivorous bipedal early dinosaurs from the Late Triassic to Early Jurassic, including Saturnalia and Thecodontosaurus. The larger Sauropods (“Lizard-Foot” Dinosaurs) in some cases grew to massive size, and were characterized by long necks and tails, relatively small heads, primarily a quadrupedal gait, and a generally herbivorous diet. Sauropods include Apatasaurus (once called Brontosaurus), Brachiosaurus, and Saltasaurus.

g. Why are marine and flying reptiles not considered dinosaurs? Give examples of these creatures

Dinosaurs are properly those animals included in the Superorder Dinosauria, a group of terrestrial reptiles characterized by their stance, by stronger ankle and knee joints, and by antorbital and mandibular fenestrae. Marine and flying reptiles come from different lines of reptiles.

The flying reptiles (in the Order Pterosaurs, or “Winged Lizards”) include the Quetzelcoatlus, Pterodactylus, and Pteranodon, among others.

Marine reptiles are in several groups, including the Superorder Ichthyopterygia and the Superorder Sauropterygia. Some well known marine reptiles include the Plesiosaurs, Ichthyosaurs and Mosasaurs.

5. Identify by description and sketches/drawings each of the following species of dinosaurs:

a. Sauropods

means "lizard-footed", are an infraorder of saurischian ("lizard-hipped") dinosaurs. They had very long necks, long tails, small heads (relative to the rest of their body), and thick, pillar-like legs. They are notable for the enormous sizes attained by some species, and the group includes the largest animals to have ever lived on land.

6. Individually or as a group, research and discuss/present the following:

a. Where the Bible speaks about the creation of the reptiles.

20 And God said, “Let the water teem with living creatures, and let birds fly above the earth across the vault of the sky.” 21 So God created the great creatures of the sea and every living thing with which the water teems and that moves about in it, according to their kinds, and every winged bird according to its kind. And God saw that it was good. 22 God blessed them and said, “Be fruitful and increase in number and fill the water in the seas, and let the birds increase on the earth.” 23 And there was evening, and there was morning—the fifth day. 24 And God said, “Let the land produce living creatures according to their kinds: the livestock, the creatures that move along the ground, and the wild animals, each according to its kind.” And it was so. 25 God made the wild animals according to their kinds, the livestock according to their kinds, and all the creatures that move along the ground according to their kinds. And God saw that it was good.
— Genesis 1:20-25 (NIV)

There are a number of other Bible texts that mention reptiles.

b. Evidences that dinosaurs really existed.

Fossils of dinosaurs have been discovered around the world. There are also fossilized dino footprints.