Platypus Ornithorhynchus anatinus Whitney Gunn David Coleman John Rice

Platypus Facts Common Name: Platypus Scientific Name: Ornithorhynchus anatinus They live for about 10 to 15 years Natural habitat is East Australia and New Guinea Carnivorous diet Call sound

History Estimate of the Monotremes-Theria divergence, time range between 160 and 120 Myr ago. The red line shows these are small mammals that developed hair, lactation, and homoeothermic.

Characteristics Has spurs on its hind feet Platypus is one of the few venomous mammals. The male platypus can delivers a poison through a spur on its hind foot. Adults do not have teeth Baby platypus are born with teeth this may be due to a “throwback” from its ancestors. Once they lose them they do not grow new teeth back. Adults do not need teeth because they use horny pads to grind their food.

Characteristics The have no true stomachs Female platypus lay eggs She lays 1-3 eggs, which she incubates between her abdomen and tail. Lactation The female platypus do not have nipples, so it’s young ones suck milk from patches on the abdomen

Evolution of Platypus

Evolution Protamine P1 protein sequence

Evolution P Distance matrix DNA Phylogenetic tree showing the relationships between monotremes, marsupials, and mammals Ech Mou Opo Pla Roo 0.7162 0.8040 0.7789 0.1030 0.7448 0.8037 0.9769 1.1324 1.2805 0.9405

Venomous Trait The venom is made up of at least 19 different substances The substance has been named the defensin-like proteins, or DLPs, because their three dimensional structure resembles that of an antimicrobial peptide known as beta-defensin.

Lactation and Eggs It has been proposed that early lactation evolved as a water source to protect porous parchment-shelled eggs from desiccation during incubation or as a protection against microbial infection. Parchment-shelled egg-laying monotremes also exhibit a more ancestral glandular mammary patch or areola without a nipple that may still possess roles in egg protection

Similarities Both are only found in Australia and New Guinea Monotreme means "one-holed," referring to the cloaca, a single hole that serves the urinary tract, anus, and reproductive tract in monotremes. Both lay eggs

Differences Echidna Platypus Has a point snout Pointy spines on coat Has duck like bill Short dark brown fur

Further Studies Recently scientist have been taking the platypus genome and comparing it to humans. A study on why they secret milk through their abdominal muscles instead of through nipples would be helpful to further understand its evolutionary process.

References http://assets0.pubget.com/pdf/8269934.pdf http://www.nature.com/nature/journal/v453/n7192/pdf/nature06936.pdf

Picture Sources http://soer.justice.tas.gov.au/2003/image/559/ilw/p-platypus_m.jpg http://www.nature.com/nature/journal/v453/n7192/pdf/nature06936.pdf