Mammals are Older Than We Thought

(Image credit: Joseph Groenke, Stony Brook University; Sculpture credit: Gary Staab, Staab studios)

A newly discovered fossil has pushed back the age of mammals by about 200-million years.

A newly discovered fossil has pushed back the age of mammals to about 200 million years. (Thanks to Dr. Anne Weil for the correction.)

Mammals and dinosaurs walked the planet at the same time, it’s just that mammals were tiny…like the size of a mouse or shrew. Scientists from Stony Brook University in New York recently made a discovery in Madagascar that not only shows some mammals were bigger than previously thought but that mammals have been around much longer than we realized.

The mammal is called Vintana sertichi. It weighed about 20 pounds and lived around 66-70 million years ago. Tulsa based paleontologist Dr. Anne Weil wrote about the groundhog sized animal for Nature Magazine. (It’s behind a paywall but if you’re so inclined…) She told me the discovery is “supercool”. She says it solves a longstanding mystery about the evolution of mammals and just how long they’ve been on Earth.

Check out the video below Courtesy of Stony Brook University

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5 thoughts on “Mammals are Older Than We Thought

  1. Mike Hopkins

    “A newly discovered fossil has pushed back the age of mammals by about 200-million years. ”

    This needs rewording. That there were mammals during the Triassic which ended about 200 million years ago has been known since before I was born. No one has ever suggested that mammals have existed 200 million years before that.

    And if we are talking about “age of mammals” as opposed to mere existence of mammals, bear in mind that the “age of mammals” like “the age of dinosaurs” or the “the reign of dinosaurs” are human constructs applied to the past. No mammal in the Mesozoic said, “I am in the ‘age of dinosaurs’ so my species better not evolve large size.” Indeed like the story the 2005 story of mammals eating non-avian dinosaurs, I am completely unsurprised that there is a 20 pound mammal in the late Cretaceous. Indeed I would not be surprised if some day a far larger mammal is dug out of Mesozoic rocks. Mammals existed with the non-avian dinosaurs for far longer than they have lived without them and the planet is a huge place. That is time and space for evolution to do a lot. Be sure to read John Wilkins’ comment in the link.

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  2. Anne Weil

    Well, I think there is a typo there. If it read ““A newly discovered fossil has pushed back the age of mammals TO about 200 million years. ” (actually even a bit older), that would be correct.

    No one has been able to show, before the last year or so, that crown-group Mammalia was that old. (Although some have argued it, those arguments have not stood up to analysis.) There has been some argument, however, over whether defining “mammal” to mean a member of crown-group Mammalia was useful. Most scientists who work on mammals use the crown group definition.

    “What is that?’ you might ask. It is the definition that defines Mammalia as being the ancestor of all living mammals, and all of its descendents (living or fossil). There were probably animals that lived prior to this common ancestor that had fur, and they may even have produced milk. They may not have had a middle ear with three bones in it, which you can’t see on the outside of a living mammal and which all living mammals also have.

    So basically, no, in the prevailing scientific view, it was not known that there were mammals during the Triassic. There were little furry relatives of mammals running around. I’m sure this seems like splitting hairs (pun intended), but just as we have discovered that not everything with feathers was a bird, not everything with hair was a mammal.

    Anne Weil

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