33.Are dinosaurs extinct? Theropod dinosaurs are the bipedal (\"two-footed\") ca

Question

33.Are dinosaurs extinct?

Theropod dinosaurs are the bipedal ("two-footed") carnivores of Tyrannosaurus rex fame that many people imagine when they think of dinosaurssharp teeth, claws, long tails, and a taste for flesh. Did these dinosaurs go extinct?

Part A

Redraw the tree in the figure below as a cladogram (i.e., with branch lengths not pinned to time scale). For simplicity, show only the branches with animal icons. Then add an outgroup to the theropods called the Sauropoda (which includes the enormous Apatosaurus); mark the origin of downy feathers, which occur in all theropods; and mark the origin of shafted feathers and wings, which occur in all the groups except Tyrannosauroidea.

Redraw the tree in the figure below as a cladogram (i.e., with branch lengths not pinned to time scale). For simplicity, show only the branches with animal icons. Then add an outgroup to the theropods called the Sauropoda (which includes the enormous Apatosaurus); mark the origin of downy feathers, which occur in all theropods; and mark the origin of shafted feathers and wings, which occur in all the groups except Tyrannosauroidea.

Source: Godefroit, P., A. Cau, H. Dong-Yu, et al. 2013. Nature 498: 359362. Tyrannosauroidea Oviraptorosauria Dromaeosauridae Troodontidea Aurornis Archaeopteryx Rahonavis Shenzouraptor Balaur Confuciusomis Euornithes (true birds") Enantiornithes 180 160 140 120 100 80 60 40 Million years ago

Explanation / Answer

Dinosaurs extinction has happened about 65 million years ago. Extinction of dinosaurs is the end of cretaceous and it is beginning of paleogenes age. There was a change in Sea levels and change in climatuc conditions also may be a reason for the extinction. Volcanoes also contribute to the threat for dinosours.

Related Questions

Navigate

• Browse (All)
• Browse 3
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.