Today I’ve been studying about the oldest-dated fossil mammal hair. (http://news.yahoo.com/cretaceous-fur-ball-ancient-mammal-spiky-hair-discovered-132251323.html
“Cretaceous Fur Ball: Ancient Mammal With Spiky Hair Discovered”
from LiveScience.com, By Elizabeth Palermo, 10/16/2015 (updated at 3:52 p.m. EDT)
Surprise, it’s not from China! Spain has a very excellent fossil site, the Las Hoyas quarry. Back in 2011, they dug up a fossil now called Spinolestes xenarthrosus. Now a report has been published in the October 14th Nature, and LiveScience had this article about it (repeated by Yahoo). Major take-away quote:
You may think that, over the course of 125 million years, the process by which mammalian hair grows would have changed somehow, but that’s not the case, Luo said. The bones of Spinolestes, which was about the size of a small rat, are proof that ancient mammals grew hair the same way as modern mammals do.
Well, I guess “bones” is somewhat metaphorical — they actually have the petrified hairs, roots, and skin. In fact, the fossil “is special because it was fossilized with so many of its parts intact.” Parts of it were preserved so well, the researchers were able to see microscopic details, using a scanning electron microscope!
There was also evidence of internal soft tissues, including the kidneys and lungs. Besides the ordinary hair, it “had hedgehoglike spines [that grew] the same way that modern-day hedgehogs and certain other mammals grow their spines.” They even found “evidence that the prehistoric fur ball suffered from a fungal skin infection known as dermatophytosis, [suffered by modern mammals].”
Hmm, there we go again – stuff supposedly over 100 million years old that looks like the same things today. And this date they’ve given the “fur ball” of 125 million years makes it almost twice as “old” as the previous comparable fossil, which was up in the rocks that don’t have dinosaurs in them. Spinolestes is placed well back in the last section of the “Age of Dinosaurs,” the Cretaceous.
The evolutionary story of mammals is fascinating. One or two fossils are dated about as old as the first dinosaurs, but there’s not much to them. There’s actually quite a bunch of different mammal fossils in the dinosaur-laden strata, but none of them appear to be the same as living mammals … nor is there any particularly strong connection between these mammals and all the highly diverse mammals that pop up in the post-dinosaur rocks, many of which are easily identifiable as belonging to modern orders.
According to the original report in Nature, “Many ecomorphotypes familiar to modern mammal fauna evolved independently early in mammalian evolutionary history.” That means that a lot of the mammals buried with the dinosaurs looked like alternate versions of the Cenozoic ones with us today (being designed to live by climbing trees like opossums, burrowing like badgers, swimming like beavers, etc.), but only in a general way and not, even to evolutionists, appearing to be the direct ancestors of the living ones.
It also says the critter had “such typical mammalian features as pelage, mane, pinna…” Pelage is the fur, and pinna is the ear, that is, the outer part that we ordinarily call the ear (I had to look that one up). We’ve already noted that this critter had spines like a hedgehog, but it also had “specialized xenarthrous articulations of posterior dorsal vertebrae, convergent with extant xenarthran mammals” which means the far end of its backbone had a design similar to that of South American sloths, armadillos, and anteaters, but again, the similarity is not reckoned to be due to evolutionary relationship.
I would very much like to see the full report (all I have access to are the Abstract and Editor’s Summary). I’m surprised there’s no mention of even looking for indications of sex organs and how it gave birth (for similarities to monotremes, marsupials, or placentals), or signs of mammary glands. Even monotremes (echidnas and platypus) at least have patches where the milk oozes out for the babies to lick. Seems to me that’s an important feature for critters called mammals, and something I thought they’d comment on, even if just to mention why they didn’t find anything, or nothing conclusive.
“A Cretaceous eutriconodont and integument evolution in early mammals,” Thomas Martin, Jesús Marugán-Lobón, Romain Vullo, Hugo Martín-Abad, Zhe-Xi Luo & Angela D. Buscalioni
Nature 526, 380–384 (15 October 2015)