Research what kind of transition fossils exist that shows evidence that mammals evolved from reptilian ancestors. Include the descriptive evidence that supports this phylogenetic link.
Ms. please give me feedback, the information was really confusing so im not sure i did it right. Transition fossils are one of the main pieces of evidence for the evolutionary theory. Transition fossils are what show the stage in between an ancestor and its descendants. The two main transitional fossils that show the relationship between mammals and reptiles are synapsids and therapsids(Mrs.Rudolph, Bio II). Synapsids are more closely related to mammals than reptiles, they are the main common ancestor for large terrestrial creatures and are also present in the oceans as the ancestors of whales and pinnipeds. All early synapsids had “a hole in the lateral surface of the skull behind the orbit” that some mammals today still have. “Early synapsids had a sprawling posture and a small brain, like most early tetrapods.” (Michel Laurin Muséum National d'Histoire Naturelle, Paris, France) Therapsids are said to have evolved from a group of synapsids called Pelycosarus which look like a big lizard with a sail on its back. The differences between Therapsids and Pelycosarus were larger teeth(canines), several structure modifications like a larger skull and a more hind like posture. Therapsids are divided into six groups, one of them being cynodonts which is the group thought to be the ancestor of mammals. ( http://www.earthhistory.org.uk/transitional-fossils/reptile-to-mammal) The transition is thought to have gone from Synapsids who were more reptile-like, to Therapsids and further on to more mammal-like creatures.(Kemp TS,University Museum of Natural History, and St John's College, Oxford).
Mrs.Rudolph Bio II class
Laurin, Michel and Robert R. Reisz. 2011. Synapsida. Mammals and their extinct relatives. Version 14 August 2011. http://tolweb.org/Synapsida/14845/2011.08.14 in The Tree of Life Web Project, http://tolweb.org/
http://www.earthhistory.org.uk/transitional-fossils/reptile-to-mammal, 25th of May 2011 J Evol Biol. 2006 Jul;19(4):1231-47. Source: University Museum of Natural History, and St John's College, Oxford, UK
Blog: Mammal Transition Fossils Transition fossils are the missing links between two different groups. They serve as key evidence for evolution and species' gradual change over time. These transitional fossils are used as evidence in Charles’s Darwin’s theory of evolution. Occidental College geologist Donald Prothero wrote about the transition fossils in his book "Evolution: What the Fossils Say and Why It Matters". There is an idea that Mammals come from Reptiles. To prove this idea there has been found a fossil of an animal half reptile, half mammal called synapsid (260 and 180 million years ago). This animal has mammal like characteristics like carrying their limbs under their body, and developing frontal teeth different from their back teeth. One group of synapsid is the therapsids. The best example of therapsids is The South African Karoo Basin
Picture of therapsids: (https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&docid=v-9p7nESkS03PM&tbnid=1OfKT8YqKg3zjM:&ved=0CAUQjRw&url=http%3A%2F%2Fwww.allmystery.de%2Fthemen%2Ftp55888-26&ei=dolpUtKMHcblkAewp4CgAg&bvm=bv.55123115,d.eW0&psig=AFQjCNFQNrVlDH5ZjxGuLcKt73o921N7Mg&ust=1382734575399042)
What are transitional fossils? Fossil remains of a creature that exhibits primitive traits in comparison with more derived organisms to which it is related. (Definition from Wikipedia.) The rise of mammals did not come from true reptiles but from synapsids which are mammal-like reptiles or reptile-like mammals. There is a lot of evidence proving that synapsids gave rise to mammals. Dimetrodon was a synapsid that lived 280 million years ago. The dimetrodon had specialized canine teeth very similar to those of modern mammals. The thrinaxodon was also a synpsid that lived 245 million years ago which was a more mammal-like than the dimetrodon. It was the began developing the secondary palate. In modern mammals this allows eating and breathing at the same time, and is also a sign of an active lifestyle. The more advanced skull allowed the thrinaxondon to chew its food which also meant it had molars to do so. Although the skull was mammal-like the skeleton was not but it did have lungs. The Diarthrognathus which lived about 210 million years ago was one which a jaw that contained both reptilian joints along with mammalian joints. (Rusty Cashman, http://www.transitionalfossils.com/#mammals) These are all examples of transitional fossils that are evidence that mammalian raised from reptile-like creatures or synapsids.
"List of Transitional Fossils." Wikipedia. Wikimedia Foundation, 16 Oct. 2013. Web. 24 Oct. 2013. . "A Few Selected Transitional Fossils." (A Few) Transitional Fossils. N.p., n.d. Web. 24 Oct. 2013. .
Ever wondered why some mammals ley eggs? This is because mammal’s decedents are reptile like animals. In reality, these ancient mammal-relatives, known as synapsis, are more closely related to living mammals than they are to any reptiles, (Kenneth D. Angielczyk). Geologists have found many fossils from the Triassic period (248-245 million years ago) that have characteristics of both mammals and reptiles (Wikipedia). These fossils have been named transition fossils; this is because they demonstrate the link between mammals and reptiles,( Glossary entry for "Transitional fossil") One example of a transition fossil is the Thrinaxodon. The Thrinaxodon was an organism that lived during the early Triassic period. In particular some reptile to mammal transition fossils document the transition from one type of jaw to another and from a; one bone ear to an ear with three bones. The Thrinaxodon developed an eardrum in the lower jaw, permitting it to hear airborne sound. Its quadrate and articular jaw bones could vibrate freely, allowing them to function for sound transmission while still functioning as jaw bones. (Talk Origins Achieve) The Thrinaxodon was a ground hovering animal that lived in burrows. It also has well defined teeth that suggest they consumed small animals like reptiles and insects. Clues to its remains found by Dr. Tim Rowe of the University of Texas suggest that the animals where more mammal like than reptile like. These animals lived in burrows and have pits in the snout area that suggest that they had whiskers. (Vincent Fernandez and others)
There are several evidences that mammals evolved from reptilian ancestors. Jaws and teeth are one of the many evidences. Scientists have discovered that differentiated teeth of mammals (incisors, canines, molars) have evolved from peg-like reptilian teeth; also, they discovered that the dentary, jaw with only one bone, from mammalian jaws have evolved from the complex reptilian jaws, jaws with five separate bones (Michael Benton, “Evidence of Evolutionary Transitions). Many years ago, Charles Darwin saw fossils of South American mammals, the giant ground sloths and glyptodonts and noticed that these species are similar to some other species, and he questioned why. Soon, Darwin discovered that all life was similar because they had evolved. It had not been created, species by species. The Galapagos finches, tortoises, and iguanas had diverged from single ancestors that arrived isolated from the rest of the world. There were now birds and mammal that had evolved through long spans of time from single ancestors (Nick Kurzenko, “Tree of Life”).
Nedin, C. (1999, January 15). All about archaeopteryx. Retrieved from http://www.talkorigins.org/faqs/archaeopteryx/info.html
Maddison, D. R. (2007, March 17). The tree of life. Retrieved from http://tolweb.org/tree/
Ms. please give me feedback, the information was really confusing so im not sure i did it right.
ReplyDeleteTransition fossils are one of the main pieces of evidence for the evolutionary theory. Transition fossils are what show the stage in between an ancestor and its descendants. The two main transitional fossils that show the relationship between mammals and reptiles are synapsids and therapsids(Mrs.Rudolph, Bio II). Synapsids are more closely related to mammals than reptiles, they are the main common ancestor for large terrestrial creatures and are also present in the oceans as the ancestors of whales and pinnipeds. All early synapsids had “a hole in the lateral surface of the skull behind the orbit” that some mammals today still have. “Early synapsids had a sprawling posture and a small brain, like most early tetrapods.” (Michel Laurin Muséum National d'Histoire Naturelle, Paris, France) Therapsids are said to have evolved from a group of synapsids called Pelycosarus which look like a big lizard with a sail on its back. The differences between Therapsids and Pelycosarus were larger teeth(canines), several structure modifications like a larger skull and a more hind like posture. Therapsids are divided into six groups, one of them being cynodonts which is the group thought to be the ancestor of mammals. ( http://www.earthhistory.org.uk/transitional-fossils/reptile-to-mammal) The transition is thought to have gone from Synapsids who were more reptile-like, to Therapsids and further on to more mammal-like creatures.(Kemp TS,University Museum of Natural History, and St John's College, Oxford).
Mrs.Rudolph Bio II class
Laurin, Michel and Robert R. Reisz. 2011. Synapsida. Mammals and their extinct relatives. Version 14 August 2011. http://tolweb.org/Synapsida/14845/2011.08.14 in The Tree of Life Web Project, http://tolweb.org/
http://www.earthhistory.org.uk/transitional-fossils/reptile-to-mammal, 25th of May 2011
J Evol Biol. 2006 Jul;19(4):1231-47. Source:
University Museum of Natural History, and St John's College, Oxford, UK
Alvaro Rojas
ReplyDeleteBio 11
Mrs. Rudolf
October 22, 2013
Blog: Mammal Transition Fossils
Transition fossils are the missing links between two different groups. They serve as key evidence for evolution and species' gradual change over time. These transitional fossils are used as evidence in Charles’s Darwin’s theory of evolution. Occidental College geologist Donald Prothero wrote about the transition fossils in his book "Evolution: What the Fossils Say and Why It Matters". There is an idea that Mammals come from Reptiles. To prove this idea there has been found a fossil of an animal half reptile, half mammal called synapsid (260 and 180 million years ago). This animal has mammal like characteristics like carrying their limbs under their body, and developing frontal teeth different from their back teeth. One group of synapsid is the therapsids. The best example of therapsids is The South African Karoo Basin
Picture of therapsids: (https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&docid=v-9p7nESkS03PM&tbnid=1OfKT8YqKg3zjM:&ved=0CAUQjRw&url=http%3A%2F%2Fwww.allmystery.de%2Fthemen%2Ftp55888-26&ei=dolpUtKMHcblkAewp4CgAg&bvm=bv.55123115,d.eW0&psig=AFQjCNFQNrVlDH5ZjxGuLcKt73o921N7Mg&ust=1382734575399042)
Sources:
http://www.livescience.com/3306-fossils-reveal-truth-darwin-theory.html
http://genesispanthesis.tripod.com/fossils/rept_mam.html
http://www.nasmus.co.za/departments/palaeontology/introduction
What are transitional fossils? Fossil remains of a creature that exhibits primitive traits in comparison with more derived organisms to which it is related. (Definition from Wikipedia.) The rise of mammals did not come from true reptiles but from synapsids which are mammal-like reptiles or reptile-like mammals. There is a lot of evidence proving that synapsids gave rise to mammals. Dimetrodon was a synapsid that lived 280 million years ago. The dimetrodon had specialized canine teeth very similar to those of modern mammals. The thrinaxodon was also a synpsid that lived 245 million years ago which was a more mammal-like than the dimetrodon. It was the began developing the secondary palate. In modern mammals this allows eating and breathing at the same time, and is also a sign of an active lifestyle. The more advanced skull allowed the thrinaxondon to chew its food which also meant it had molars to do so. Although the skull was mammal-like the skeleton was not but it did have lungs. The Diarthrognathus which lived about 210 million years ago was one which a jaw that contained both reptilian joints along with mammalian joints. (Rusty Cashman, http://www.transitionalfossils.com/#mammals) These are all examples of transitional fossils that are evidence that mammalian raised from reptile-like creatures or synapsids.
ReplyDelete"List of Transitional Fossils." Wikipedia. Wikimedia Foundation, 16 Oct. 2013. Web. 24 Oct. 2013. .
"A Few Selected Transitional Fossils." (A Few) Transitional Fossils. N.p., n.d. Web. 24 Oct. 2013. .
Ever wondered why some mammals ley eggs? This is because mammal’s decedents are reptile like animals. In reality, these ancient mammal-relatives, known as synapsis, are more closely related to living mammals than they are to any reptiles, (Kenneth D. Angielczyk). Geologists have found many fossils from the Triassic period (248-245 million years ago) that have characteristics of both mammals and reptiles (Wikipedia). These fossils have been named transition fossils; this is because they demonstrate the link between mammals and reptiles,( Glossary entry for "Transitional fossil") One example of a transition fossil is the Thrinaxodon. The Thrinaxodon was an organism that lived during the early Triassic period.
ReplyDeleteIn particular some reptile to mammal transition fossils document the transition from one type of jaw to another and from a; one bone ear to an ear with three bones. The Thrinaxodon developed an eardrum in the lower jaw, permitting it to hear airborne sound. Its quadrate and articular jaw bones could vibrate freely, allowing them to function for sound transmission while still functioning as jaw bones. (Talk Origins Achieve)
The Thrinaxodon was a ground hovering animal that lived in burrows. It also has well defined teeth that suggest they consumed small animals like reptiles and insects. Clues to its remains found by Dr. Tim Rowe of the University of Texas suggest that the animals where more mammal like than reptile like. These animals lived in burrows and have pits in the snout area that suggest that they had whiskers. (Vincent Fernandez and others)
http://link.springer.com/article/10.1007%2Fs12052-009-0117-4 2009(Kenneth D. Angielczyk)
(April 19, 2011). http://palaeos.com/evolution/glossary.html#transitional
http://www.ucmp.berkeley.edu/synapsids/rowe/thrinax.html
http://en.wikipedia.org/wiki/Thrinaxodon
http://www.talkorigins.org/indexcc/CC/CC215.html
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0064978 June 21, 2013 Fernandez V, Abdala F, Carlson KJ, Cook DC, Rubidge BS,
Mammal Transitionary Fossils
ReplyDeleteThere are several evidences that mammals evolved from reptilian ancestors. Jaws and teeth are one of the many evidences. Scientists have discovered that differentiated teeth of mammals (incisors, canines, molars) have evolved from peg-like reptilian teeth; also, they discovered that the dentary, jaw with only one bone, from mammalian jaws have evolved from the complex reptilian jaws, jaws with five separate bones (Michael Benton, “Evidence of Evolutionary Transitions).
Many years ago, Charles Darwin saw fossils of South American mammals, the giant ground sloths and glyptodonts and noticed that these species are similar to some other species, and he questioned why. Soon, Darwin discovered that all life was similar because they had evolved. It had not been created, species by species. The Galapagos finches, tortoises, and iguanas had diverged from single ancestors that arrived isolated from the rest of the world. There were now birds and mammal that had evolved through long spans of time from single ancestors (Nick Kurzenko, “Tree of Life”).
Nedin, C. (1999, January 15). All about archaeopteryx. Retrieved from http://www.talkorigins.org/faqs/archaeopteryx/info.html
Maddison, D. R. (2007, March 17). The tree of life. Retrieved from http://tolweb.org/tree/