Identifies a theme that is revealed in the conversation between Abigail and John Proctor.

Explanation:

Dinosaurs are a group of land-dwelling reptiles which had some unique anatomical features that distinguish them from known living reptiles.  Like all reptiles, dinosaurs were vertebrates, air-breathing, and had scales.  They laid eggs, just like most extant reptiles.  But dinosaurs had some features that are not found in known living reptiles – namely a unique hip structure.  Modern reptiles have a hip design that places their hind legs out to the side, giving them a sprawling structure.  But dinosaurs had their legs underneath their hips, giving them an upright posture.  So, dinosaurs were not merely larger versions of modern reptiles, but were a unique design of reptile.

Note that flying reptiles such as the Pteranodon are not technically dinosaurs since they do not have the required hip structure.  Likewise, sea-dwelling reptiles such as plesiosaurs and ichthyosaurs are not true dinosaurs because they are not land animals.  However, these creatures are often included in books on dinosaurs.

Taxonomically, dinosaurs are a superorder consisting of two orders: saurischia and ornithischia.  Saurischian dinosaurs are called “lizard hipped.”  This name is somewhat misleading because, as mentioned above, their hips are designed for erect posture and not for sprawling.   However, in saurischians, the pubis bone points forward, away from the ischium as it does in lizards.  Conversely, ornithischian dinosaurs are called “bird-hipped” because they had a pubis bone that points backwards along with the ischium as it does in modern birds.

The lizard-hipped dinosaurs are divided into two main branches: Theropods and Sauropodomorphs.  Theropods were bipedal and included varieties such as Tyrannosaurus rex, Velociraptor, Deinonychus, Dilophosaurus, and Compsognathus.  Sauropodomorphs were quadrupeds with long necks and long-tails.  They include varieties such as Apatosaurus, Brachiosaurus, and Diplodocus.

Thyreophora, Marginocephalia, and Ornithopoda comprise the bird-hipped dinosaurs.  Thyreophora refers to the armored dinosaurs, such as Ankylosaurus and Stegosaurus.  Marginocephalia includes both the horned dinosaurs, referred to as Ceratopsians (such as Triceratops), and the bone-headed dinosaurs (Pachycephalosauria).  Ornithopoda includes varieties such as the Hadrosaurs (“duck billed dinosaurs”), and Iguanodons.

Hope this helped you!