Stanford Report.com 7 February 2003. 20 March 2004. < http://news service.stanford.edu/news/2003/february12/ichthyosaur-25.html> Motani, Ryosuke. “Rulers of the Jurassic Seas”. ScientificAmerican.com 19 December 2000.
Today’s whales have mammalian characteristics, which prove that they have evolved from a common ancestor of the mammal. A whale’s fin also has traits that are common of many species. The fin seems to be similar to that of a fish, but the bones on the inside of the fin are similar to those on a bird’s wing, a monkey’s arm, and a frog’s limb. This seems to be proof that these organisms, and many others, all evolved from a common ancestor. Other proof that whales have evolved over time lies in Egypt in the Valley of Whales, where over 400 fossils of whales currently lie.
These animals had unusual triangular teeth similar to those of whales. This is why scientists long believed that whales evolved from a form of Mesonychid. More recent molecular phylogeny data suggest that whales are more closely related to the artiodactyls, specifically the hippopotamus. The strong evidence for a clade combining cetaceans and artiodactyls is further discussed in the article “Cetartiodactyla”. However, the anthracothere ancestors of hippos do not appear in the fossil record until millions of years after Pakicetus, the first known whale ancestor(Strauss, no date).
The Debate Over Dinosaur Nostril Positioning Where should the nostril on dinosaur models be placed? Although it seems like a rather simple question, it is a topic that has been recently researched so that scientists can feel reassured in creating anatomically correct models of dinosaurs. Amniotes (a group which in the Triassic spilt into reptiles and synapsids and which include dinosaurs), have large nasal openings, but since the nostril is made up of flesh and cartilidge, it is almost always not preserved in the fossil record (Lauren and Gauthier 1996). These were often huge in dinosaurs, such as the sauropods, hadrosaurines, and ceratopsids, so that there are several places in which the nostrils could be placed. For many years, scientists have placed the nostrils on dinosaurs in the caudal position, which is located on the top of the head.
Walking With Whales. Nature 413, 259-260. September 2001. www.nature.com/nature/journal/v413/n6853 Thewessen, J. G. M., Williams, E. M., Roe, L. J. & Hussain, S. T. Nature 413, 277-281. 2001.
2000. http://whales.greenpeace.org/whaling. Accessed 5/9/04. Institute of Cetacean Research. 2002. http://www.icrwhale.org/eng-index.htm. Accessed 5/9/04.
74:184-185. (DOI:10.1007/s10641-005-2229-1). Whale Shark. Whale Shark Fact File. Retrieved March 9, 2014, from http://www.arkive.org/whale-shark/rhincodon-typus/.
How did this happen? How did mammals come to be living in the ocean? Where did whales come from, and how are they related to other mammals, the ones who live on land? This paper is intended to examine some of the evidence that has emerged in recent years in respect to the last question. In 2001, in Pakistan, scientists unearthed fossils dating from the Eocene epoch that provide a few answers about the land-based origin of cetaceans.
The dorsal fin normally appears some time after the... ... middle of paper ... ...ws about blue whales coming from the rest of the world's oceans. California waters may now represent some of the most critical large whale habitats in the world. Bibliograpghy 1. Boitani, Luigi and Bartoli, Stefania 1983. Simon and Schuster's Guide to Mammals.
Dinosaur Fossil Discoveries in Antarctica The chance of two different research groups finding two different fossils that are in fact two different kinds of species within the course of a week is close to impossible. However, this rare and lucky occurrence in the paleontology world has occured. Two research teams have retrieved fossils of two different dinosaurs in Antarctica that might possibly be unknown species. Judd Case and James Martin discovered bones, specifically those of the lower legs and feet, as well as the animal’s upper jaw and teeth. These fossils are said to be related to the carnivorous theropods, such as tyrannosaurs and velociraptors.