CLONING DINOSAUR1 - hip morphology The...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
CLONING DINOSAURS What is a Dinosaur? 1) occured from the mid-late Triassic to the end of the Cretaceous (220 mil. years ago, mya to 65 mya) 2) they are "reptiles", (but as we know this is not a natural group), 3) they were terrestrial (excludes marine plesiosaurs, ichthyosaurs, mososaurs, 4) Upright pillared legs (an obvious structural "necessity" given their weight. Only the latter is a good "defining" character, cladistically, since there are plenty of other organisms that fit descriptions 1-3 that are not dinosaurs. Moreover, some mammals and birds have pillared legs. There are two general groups of dinosaurs based on
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: hip morphology The Saurischia (reptile-hipped) and the Ornithischia (bird-hipped). In both groups the ilium and the ischium have relatively similar forms, but in the Ornithiscia, the pubis has a narrow rod-shaped extension running ventrally and posteriorly along the ventral side of the ischium. In the Saurischia, the pubis extends ventrally and anteriorly and only articulates with the ischium (and ilium) to form the hip "socket". Most of the Ornithischia also have a horn covered beak and bony rods and vertebral spines....
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online