It lives in freshwater systems along the east coast of australia, but fossil evidence shows that platypuses used to have a wider distribution. The analysis confirms that the platypus was the earliest offshoot of the mammalian family tree, graves noted The group of animals called monotremes—which includes the platypus and the closely. What are the platypus’s genetic relatives The platypus’s genetic relatives are monotremes, the most ancient group of mammals still in existence, sharing common ancestry with echidnas and tracing back to a lineage that diverged from other mammals (placental mammals and marsupials) over 166 million years ago A unique place in the mammalian tree the platypus ( ornithorhynchus.
The platypus and its cousins, the echidnas, are all that remains of the monotremes, which branched from the marsupials and eutherians some 166 million years ago. The current estimate for when monotremes diverged from other mammals is 166 million years ago (mya) [7]. A gap of 35 million years subsequently separates the youngest mesozoic monotremes from the oldest cenozoic monotreme, monotrematum sudamericanum, which is a paleocene stem ornithorhynchid from southern south america. Molecular phylogenetics suggests that monotremes split from the rest of mammalia approximately 250 million years ago, during the triassic period, with the platypus lineage emerging around 166 million years ago [1]. Divergence was reinforced by multiple translocations in monotreme sex chromosomes, the first of which supplied a novel sex determining gene The distance data support the view that the echidna and platypus lineages diverged from their last common ancestor at least 50 to 57 ma (million years ago) and that monotremes diverged from marsupials and eutherian mammals about 163 to 186 ma.
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