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|    talk.origins    |    Evolution versus creationism (sometimes    |    142,579 messages    |
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|    Message 141,699 of 142,579    |
|    John Harshman to RonO    |
|    Re: Dinos with hooves (2/2)    |
|    30 Oct 25 13:14:17    |
      [continued from previous message]               >>>>>>>>> > they were weasel like ancestral carnivores, so my guess is        >>>>>>>>> that they        >>>>>>>>> > could have reevolved claws to be more arboreal.        >>>>>>>>>        >>>>>>>>> Where do you get this figure of 30 million years?        >>>>>>>>>        >>>>>>>> The common ancestor of extant carnivores existed around 55        >>>>>>>> million years ago, and that is around 30 million years after        >>>>>>>> that common ancestor's lineage split off from the horse lineage.        >>>>>>>> Plenty of time to reevolve claws.        >>>>>>>        >>>>>>> The relevant clawed clade is Ferae, not Carnivora. (To the best        >>>>>>> of my knowledge miacids are not hooved; viverravids are not        >>>>>>> hooved; oxyaenids are not hooved; hyaenodonts are not hooved;        >>>>>>> pangolins are not hooved; and pantolestids are not hooved.) The        >>>>>>> consensus date for Ferae is 65 million years ago. Wikipedia gives        >>>>>>> a date for 73-85 million years for Scrotifera, but the relevant        >>>>>>> nodes, depending on topology, are Zooamata or Ferungulata, which        >>>>>>> are younger.        >>>>>>>        >>>>>>> As support for hooves as a convergent trait, not all mesonychians        >>>>>>> (which are stem artiodactyls) possessed hooves. However there is        >>>>>>> dispute whether the hoofless mesonychians (arctocyonids) are        >>>>>>> stem- artiodactyls.        >>>>>>        >>>>>> It's also the case that not all (or any??) stem-perissodactyls are        >>>>>> hooved, and even some crown-perissodactyls aren't (chalicotheres).        >>>>>> I'd say that convergence in hoofiness is considerably more        >>>>>> parsimonious given the data, even forgetting about Dollo's Law.        >>>>>>        >>>>>        >>>>> If they needed to wait to find the dino mummies before they could        >>>>> determine that dinos had hooves what is the fossil evidence that        >>>>> these lineages started with claws instead of hooves?        >>>>        >>>> Well, first of all, they didn't need to wait. The bones,        >>>> specifically the unguals, are all the evidence needed.        >>>>        >>>>> Are they just going by reduction in toes or no reduction in toes?        >>>>        >>>> No. It's the shape of the unguals.        >>>        >>> Except no one noticed in centuries.        >>       >> This is just not true. These mummies are merely direct confirmation       >> of what we've known for years, with added, typical Nature-bait       >> hype. >        > Except, I can't recall it ever being mentioned on TO before.              Perhaps you need to get out more.               >>>>> Even feet with no reduction in toes to form some existing hoof        >>>>> morphologies can still have hooves. The dinos demonstrate that.        >>>>        >>>> True, though the dinosaurs in question actually do have reduced        >>>> numbers of toes. But this isn't about the number of toes. Again, the        >>>> form of the unguals is the evidence.        >>>>        >>> Pakecetus has normal looking toes, but they claim that it had claw        >>> like hooves because it has the artiodactyl ankle.        >>       >> That's silly. The ankle isn't connected to the toes. Or are you       >> making an intrinsically phylogenetic claim? >>       > It is just what was claimed in the article that I read. Pakecetus       > was claimed to likely have had claw like hooves because it had the       > artiodactyl ankle of other hooved animals. The Wiki doesn't even       > mention hooves on it's toes. The skeleton just has normal looking       > toes. https://en.wikipedia.org/wiki/Pakicetus       The reason to suppose it might have hooves is because the double-pulley       astragalus is a basal synapomorphy of artiodactyla. Not sure how basal       hooves are. But of course modern whales don't have them, so the anatomy       of the unguals is really all you have to go by. The astragalus is       irrelevant.              --- SoupGate-Win32 v1.05        * Origin: you cannot sedate... all the things you hate (1:229/2)    |
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