Mammal-Like Reptiles

Excavating Vertebrate Fossils

Jeff Good

http://www.rareresource.com/photos/dinosaur-gallery/Dimetrodon5.jpg

Synapsids Ancient ancestors of mammals Temporal fenestra Heterodont Fewer bones in jaw then reptiles Includes the Pelycosaurs and Therapsids

http://reptilis.net/wordpress/wp-content/uploads/2010/06/dimetrodon-300x177.jpg

Pelycosaurs Carboniferous – Permian periods Tetrapods Suspected to be ectotherms Elongated vertebral spines on tail or back (sails) Dentition suggests chewing as well as carnivores,

omnivores and herbivores No epidermal scales; had skin covered in osteoderms

overlain by scutes

http://en.wikipedia.org/wiki/File:CotylorhynchusDB2.jpg

http://en.wikipedia.org/wiki/File:Ophiacodon_mirus.jpg

http://images4.wikia.nocookie.net/__cb20090316233158/fossil/images/b/bf/Edaphosaurus_BW.jpg

http://planetdi.startlogic.com/dinosaur_list/images/dimetrodon_rm.jpg

Therapsids Permian – Triassic Period Greater temporal fenestra Further differentiated teeth Secondary palate Fossil records suggest hair Most mammal-like: Cynodonts

http://scienceblogs.com/loom/wp-content/blogs.dir/453/files/2012/04/i-5631005b94ef02e2d1f4fb296f6e80f5-Therapsid%20Morph%20test.jpghttp://en.wikipedia.org/wiki/File:Belesodon_magnificus.JPG

Rise of the Endotherm The Secondary Palate:

Separates the nasal cavity from the oral cavity Allows breathing while eating Suggests endothermic organisms due to the requirement of high

metabolic activities: more breathing, more eating Eventually gave rise to secondary palate in dinosaurs

http://palaeos.com/vertebrates/cynodontia/cynodontia.html

http://en.wikipedia.org/wiki/File:Inostrancevia_BW.jpg

http://en.wikipedia.org/wiki/File:Estemmenosuchus_BW.jpg

http://en.wikipedia.org/wiki/File:Thrinaxodon_BW.jpg

http://upload.wikimedia.org/wikipedia/commons/3/39/Oligokyphus_BW.jpg

Works Cited http://www.truthinscience.org.uk/tis2/index.php/component/content/articl

e/270.html http://en.wikipedia.org/wiki/Synapsid http://tolweb.org/Synapsida http://en.wikipedia.org/wiki/Pelycosaur http://dinosaurs.about.com/od/otherprehistoriclife/a/beforedinos_2.htm http://books.google.com/books?

id=Hl_JvHqOwoIC&pg=PA481&lpg=PA481&dq=Secondary+palate+endotherms&source=bl&ots=NRm1S_wKyK&sig=_dqKZ6bfmqPBi4eikB4yv2HzxJo&hl=en&sa=X&ei=OKLzUKasK4q09QSNp4CIDg&ved=0CDgQ6AEwAg#v=onepage&q=Secondary%20palate%20endotherms&f=false