Essay about The Ancient Relatives of Mammals

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The mammalian line of descent reaches back to over 300 million years. The ancient relatives of mammals were extremely different in terms of appearance from living mammals, and are often mistaken for reptiles (for example dinosaurs). In reality though, these relatives of mammals, called synapsids, are more like mammals than reptiles. Synapsids are often described as “mammal-like reptiles” because they show both reptilian and mammalian traits. They lived right before the Mesozoic Era, during the Permian Period (286-251 mya). Synapsids derive their name from the fact that they had only one temporal opening on each side of the skull (called laterotemporal fenestrae), just like all mammals. Many synapsids had features that were considered…show more content…
They are believed to have hunted larger herbivores in packs (similar to wolves). Lystrosaurus was another hippo-like aquatic creature. Cistecephalus lived underground, where it most likely dug for insects and worms. Estemmenosuchus was another Permian carnivore whose skull had many bony outgrowths. According to Neo-Darwinian theory, all the functional diversity (the various synapsid types) was wiped out as the reptiles of the Mesozoic Era overtook the synapsids. It is usually said that only the basic structural plan of modern day mammals was derived from the synapsids. This view is technically flawed because in terms of fossilized remains (the only basis by which the structure of an extinct animal can be remade), only a small amount of traits consistently distinguished mammals from reptiles. In damaged and fragmented fossils, these traits are practically undetectable. So how can one tell what the basic structural plan that was derived from synapsids was? Regardless of this, only one thing is known for sure - Non-mammalian synapsids did not evolve from reptiles. We know for a fact that non mammalian synapsids have something to do with the origin of mammals, but what happened to these fascinating creatures during the Mesozoic Era and how they gave rise to “real mammals” is unknown. The information we have on these unique group of animals is in fact very hazy and confusing, but perhaps with more researchers and new information, the
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