Platypus Hypothesis

The platypus (Ornithorhynchus anatinus) is a mysterious animal that still has scientist, specially taxonomist, at a conundrum about their evolutionary ancestors. The platypus' mixed characteristics of avian, reptilian, and mammalian features have fascinated people since the nineteenth century. When the platypus was first discovered by European scientist though that the animal was a hoax, and to this day the platypus is still an evolutionary puzzle waiting to be solved (Brian Hall.) The combination of characteristics of mammal and reptile is also thought to be the missing link to reptiles and mammals and many scientist are still in the search for more answers.

The platypuses avian similarities are their bill shape and the webbed feet similar

Hypothesis

The platypus still lay eggs because their monotemata ancestors took to the water and they have more similarities to reptiles. Results and Discussion

Fossil record for the platypus is definitely not abundant, but the few ancestors that have been discovered do inform us more about the present day platypus. The first fossil found was named Obdurodon insignis this species was classified as an ancestor of the Ornithorhynchus anatinus by the upper molar teeth and some shreds of the mandibula. Although adult platypuses do not have molars, the juvenile platypuses do. They juvenile platypuses loose their teeth and gets replaced by horney grinning paths (Retief, Winkfein & Dixon.) Steropodon galmani was the second fossil found and again it was classified as the ancestor of our present platypus by the molar teeth. The Steropodon galmani is dated to have lived back to 110 million years ago (MYA) in the Cretaceous period. This is the last period in which the dinosaurs existed. Last but not least the most recent discovery was a complete skull of the Obdurodon dicksoni that lived in the Miocene epoch. This new species also had permanent teeth as the other two ancestors (Brian Hall.) The Obdurodon dicksoni bill was more of a spoon shape than a square duck bill and was from Riversleigh area in Australia and smaller and shorter in Steropodon galmani. These types

Or maybe it was a defensive mechanism to camouflage with dinosaurs eggs, or it just simply happens to be the evolutionary lineage to their reptile ancestors. Going back to their reptile and bird like similarities, it appears that they are closer to the reptiles. As mentioned before their bone structure similarities in their pectoral gridles and splayed legs increase their lineage to reptiles than to bird therefore making the platypus more of a reptile than bird. Also, the venomous sting of the platypus could be considered a more reptilian like trait; that is, the venom itself is made up of similar genetic material to the venom in reptiles yet both venoms evolved independently (Nat Geo.) Another similarity that they have is that both reptiles and platypuses have a cloaca. This means that they both have a single external digestive opening also used for excretion, and reproduction. Platypuses eggs also have more similarities to those of reptiles in how the layer of the egg is produced inside the platypus. In male platypuses their testes are inside the abdomen rather than a scrotum, and the sperm they produce is a thread shape similar to those in reptiles (Tom