tag:blogger.com,1999:blog-3653345901774701895.post6340313455912313702..comments2024-03-23T12:02:36.626-07:00Comments on Mark P. Witton's Blog: The horns of Arsinoitherium: covered in skin or augmented with keratin sheaths?Mark Wittonhttp://www.blogger.com/profile/02524696111911168322noreply@blogger.comBlogger19125tag:blogger.com,1999:blog-3653345901774701895.post-53488011638562592462017-12-18T19:47:39.007-08:002017-12-18T19:47:39.007-08:00Do we know if Arsinotherium was sexually dimorphic...Do we know if Arsinotherium was sexually dimorphic (in either horns or body size)?Anonymoushttps://www.blogger.com/profile/09113709144577887811noreply@blogger.comtag:blogger.com,1999:blog-3653345901774701895.post-38194418392997083982017-10-02T14:34:46.529-07:002017-10-02T14:34:46.529-07:00Whoa! Have a look at this page about annual sheep ...Whoa! Have a look at this page about annual sheep horn growth.<br />http://priscilla.saltmarshranch.com/2014/01/19/sheep-annual-horn-growth/<br />There are some great images of sheep with white spotting genes and where the white is over the horns they appear translucent making the increased blood flow during growth appear pink. Nick Fonsecahttps://www.blogger.com/profile/18280007564769043641noreply@blogger.comtag:blogger.com,1999:blog-3653345901774701895.post-68640806714305458552017-10-02T14:20:09.800-07:002017-10-02T14:20:09.800-07:00I would love to see images of different stages of ...I would love to see images of different stages of growth as the horn grows longer over time. I wonder if the horn core grows at the same rate as the keratin or if it is outpaced by the keratin and if that makes a difference in how the ends up looking. Of course whenever you use google to search for horn growth it inevitably throws in deer because people can't tell the difference between antlers and horns. However, when it happened I stumbled on "cactus bucks" in deer which are not very similar but have very striking antlers. Weird stuff going on there for sure. Nick Fonsecahttps://www.blogger.com/profile/18280007564769043641noreply@blogger.comtag:blogger.com,1999:blog-3653345901774701895.post-10058499510631423492017-09-29T13:50:49.854-07:002017-09-29T13:50:49.854-07:00Recent studies on embrythopod biogeography and rat...Recent studies on embrythopod biogeography and rate of expansion imply that they are laurasian, possibly related to perissodactyls as many other Paleogene ungulate groups.<br /><br />Remember, paenungulates and prissodactyls converged closely on many anatomical details.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-3653345901774701895.post-44811422496118602632017-09-29T09:45:05.070-07:002017-09-29T09:45:05.070-07:00I don't want to be dismissive of molecular con...I don't want to be dismissive of molecular concensus, but this is about a fossil taxon and there is no way to prove what is or isn't an Afrothere.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-3653345901774701895.post-63649390206281300132017-09-29T09:06:36.605-07:002017-09-29T09:06:36.605-07:00As good time as any to point out that embrythopods...As good time as any to point out that embrythopods might not have been afrotheres after all.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-3653345901774701895.post-70454616672816407502017-09-27T10:45:06.288-07:002017-09-27T10:45:06.288-07:00Also makes me wonder about the nasal projections o...Also makes me wonder about the nasal projections of brontotheres, specifically embolotheres. Zachary Millerhttps://www.blogger.com/profile/05035947146927565746noreply@blogger.comtag:blogger.com,1999:blog-3653345901774701895.post-13361622993888704502017-09-27T08:18:01.252-07:002017-09-27T08:18:01.252-07:00Yep - all those structures are produced with soft-...Yep - all those structures are produced with soft-tissue, not altering bone shape (illustrative example: http://animaldiversity.org/collections/contributors/phil_myers/horns_antlers/horn_and_core/medium.jpg). <br /><br />Keratinous sheaths grow like mollusc shells do whereby altering the material thickness (either around the entire structure or just in one region) produces all manner of shapes as the horn or shell grows. This can be deliberate or influenced by other factors. Temperate-living bovids, for instance, tend to have banding instilled by their ability to produce more horn in summer than the winter. In all likelihood, we're not representing the true diversity of shape in the keratinous horns of fossil animals.Mark Wittonhttps://www.blogger.com/profile/02524696111911168322noreply@blogger.comtag:blogger.com,1999:blog-3653345901774701895.post-14908099911486768562017-09-27T08:11:11.778-07:002017-09-27T08:11:11.778-07:00That's interesting - I didn't know that. B...That's interesting - I didn't know that. But if these extinct antilocaprids used a pronghorn-like mechanic of shedding their sheath annually, that might give the horn core time to change shape when it's only covered in skin. Certainly among living species, I don't think the ability to change the shape of a horn core within a permanent keratinous sheath is known.Mark Wittonhttps://www.blogger.com/profile/02524696111911168322noreply@blogger.comtag:blogger.com,1999:blog-3653345901774701895.post-41231824687751989202017-09-27T08:08:52.288-07:002017-09-27T08:08:52.288-07:00I'm basing this mostly on artwork, but must ad...I'm basing this mostly on artwork, but must admit that I've not performed an exhaustive search. I'm mostly thinking of works by classic palaeoartists - maybe there's more variation out there that I realised.Mark Wittonhttps://www.blogger.com/profile/02524696111911168322noreply@blogger.comtag:blogger.com,1999:blog-3653345901774701895.post-26873155461930956112017-09-26T14:28:17.752-07:002017-09-26T14:28:17.752-07:00I'm guessing the textures you mention presumab...I'm guessing the textures you mention presumably form as layers of keratin are laid down. Presumably the horizontal ribs are similar to growth rings? We could assume that those bumps in the illustration form at the base of the horn as it grows and are pushed toward the tip of the horn as the animal matures. Nick Fonsecahttps://www.blogger.com/profile/18280007564769043641noreply@blogger.comtag:blogger.com,1999:blog-3653345901774701895.post-85138111024367183062017-09-25T22:33:05.068-07:002017-09-25T22:33:05.068-07:00One niggle. There are extinct antilocaprids (pron...One niggle. There are extinct antilocaprids (pronghorn relatives) in which the bony part of the horn is forked. Suggesting that bovid style cranial ornament isn't necessarily incompatible with complex shapes at the tip.Allen Hazenhttps://www.blogger.com/profile/05223023647802175202noreply@blogger.comtag:blogger.com,1999:blog-3653345901774701895.post-62560975090069564482017-09-25T15:46:22.902-07:002017-09-25T15:46:22.902-07:00There's something particularly gratifying abou...There's something particularly gratifying about the bovid argument here...<br /><br />Although:<br /><br />"This is not a typical reconstruction - Arsinoitherium has been reconstructed with 'regular' mammalian skin (perhaps better termed 'villose skin' - Hieronymus et al. 2009) on its horns for decades..."<br /><br />"The idea that a keratinous sheath might have existed in Arsinoitherium might seem odd..."<br /><br />I get a strange feeling that I've been living under a palaeontological rock - or just didn't pay Arsinoitherium due attention - because I was completely unaware of the 'skin-covered horns' consensus, and don't think the keratin sheath seems odd at all. Quite the reverse.<br /><br />But that's why I like visiting this blog. Always learning something!Warren JBhttps://www.blogger.com/profile/11743987856127631574noreply@blogger.comtag:blogger.com,1999:blog-3653345901774701895.post-85138647211898243412017-09-25T15:23:08.826-07:002017-09-25T15:23:08.826-07:00"Since the matter of Arsinoitherium horns is ..."Since the matter of Arsinoitherium horns is covered"<br /><br />I see what you did there.Warren JBhttps://www.blogger.com/profile/11743987856127631574noreply@blogger.comtag:blogger.com,1999:blog-3653345901774701895.post-62484149640303025002017-09-25T10:44:58.891-07:002017-09-25T10:44:58.891-07:00"Because keratin sheaths are inert, dead and ..."Because keratin sheaths are inert, dead and tough tissue, they cannot be remodelled once they are formed. This dictates that the growing bony core has to forever comply with the shape of the horn sheath and cannot change shape much over time. Size changes can be accommodated as wider and longer sheath layers can cover expanding horn cores, but it is not possible to form a more complex shape - say a branch or spur - at the tip of the horn. And before anyone mentions pronghorns: their horn branches are entirely soft-tissue: the bony core retains a simple shape."<br /><br />How does this then apply to the development of the shapes and textures we do see on bovid horns, such as the furrowed or "ribbed" look (for lack of a better term), or even the bumpy projections on your Arsinotherium reconstructions?A.https://www.blogger.com/profile/07312320463906801670noreply@blogger.comtag:blogger.com,1999:blog-3653345901774701895.post-42070279421175293652017-09-25T07:00:59.379-07:002017-09-25T07:00:59.379-07:00Toys seem to be the one area where the keratinous ...Toys seem to be the one area where the keratinous covering is preferred to the skin covering.<br /><br />http://www.thebigtheater.com/images/products/thebigzoo/400/072830-29.jpg<br /><br />http://dinotoyblog.com/2015/10/27/arsinoitherium-collecta/Andrew Raymond Stückhttps://www.blogger.com/profile/12080621275951453768noreply@blogger.comtag:blogger.com,1999:blog-3653345901774701895.post-84039460015964736212017-09-25T02:03:09.376-07:002017-09-25T02:03:09.376-07:00Faxcinating stuff.Faxcinating stuff.Michaelhttps://www.blogger.com/profile/07174422312354863164noreply@blogger.comtag:blogger.com,1999:blog-3653345901774701895.post-67059800086093674002017-09-25T00:20:10.876-07:002017-09-25T00:20:10.876-07:00I'm not an expert on Uintatherium at all, and ...I'm not an expert on Uintatherium at all, and the worst thing to do here would be to make a snap suggestion based on a rapid Google image search.<br /><br />...but, based on a rapid Google image search, the textures on the Uintatherium skull horns, bosses etc. seem less differentiated from the rest of the skull than they are in Arsinoitherium. If - and that's the sort of 'if' that should be in red, in size 72 font and underlined - that's an accurate assessment, they might just be covered in facial skin.Mark Wittonhttps://www.blogger.com/profile/02524696111911168322noreply@blogger.comtag:blogger.com,1999:blog-3653345901774701895.post-74879732450444956562017-09-24T14:16:56.911-07:002017-09-24T14:16:56.911-07:00Those Arsinoitherium reconstructions are so fresh ...Those Arsinoitherium reconstructions are so fresh and fantastic!<br />Since the matter of Arsinoitherium horns is covered, Im now curious about how would you interpret the weird headgear of the other bizarre horned giant Uintatherium.Anonymousnoreply@blogger.com