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| Some turtle facts | |
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| Topic Started: Aug 20 2017, 09:18 PM (341 Views) | |
| Carlos | Aug 20 2017, 09:18 PM Post #1 |
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Adveho in me Lucifero
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https://blogs.scientificamerican.com/tetrapod-zoology/letters-from-the-world-of-turtle-evolution/ |
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Lemuria: http://s1.zetaboards.com/Conceptual_Evolution/topic/5724950/ Terra Alternativa: http://s1.zetaboards.com/Conceptual_Evolution/forum/460637/ My Patreon: https://www.patreon.com/Carliro ![]() | |
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| kusanagi | Aug 22 2017, 08:11 AM Post #2 |
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Adolescent
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As usual for Naish, he provides good summaries but little depth: like he's churning stuff out to fill a quota between the real pieces but too often he forgets to follow up. Stuff about giant tortoises for example, and early turtle phylogeny, needs more depth. But I do hope he writes more about the giant turtles to dispel a few myths. (While I'm at it, Wonambi was present in southern parts of Australia when the climate was cooler than today: so if reptiles function better as giants in warm climates they can still function at large sizes in temperate ecosystems. Similarly some interpretations of certain late Permian ecosystems and their inhabitants, would have large ectotherms in cold climates: if only subsets of dicynodonts and cynodonts were warm blooded. Oh yea and crypto nerds might have had a reason to assume big ectotherms in Scottish and Canadian lakes, though with modern knowledge of plesiosaur metabolism and all those cameras watching the lake surfaces, it becomes a bit redundant...) Unfortunately he repeats a misunderstanding himself by saying humans hunted meiolanids to extinction when no humans of any racial or culture area ever reached Lord Howe till Europeans arrived and the horned turtles were already gone - a reminder not all Pleistocene/Holocene extinctions are anthropogenic. In fact, in the cases of Howe and Aldabra its impossible this was the case. Did protostegids have that wierd warm bloodedness thing like Dermochelys? Would make sense it evolved in the Mesozoic alongside that of mosasaurs. But I'm still interested as to why some sea creatures become endothermic and it never involves the leaky cell method or parental care. Certain pelagic teleosts, a clade of sharks and leatherbacks all have to be understood apart from hot blooded land animals for this reason and the modern leatherback is the odd one out, ecologically. It is also the only warm blooded sea reptile to exist though at least four clades of extinct sea reptiles were warm blooded - twice among platynotes, the pistosauroids and the ichthyosaurs. Protostegids were ammonoid feeders and must have at least hunted prey more likely to dart away, even if those ammonoids were slow. A great number of Cretaceous ammonoids were actually streamlined and protostegids must fit into a persuit predator guild if they were regular prey. If a fast and generalised sea turtle was the ancestor of both protostegids and D. the metabolism of the latter makes more sense (inductively). It is not gigantothermy as the public believe, as baby leatherback turtles are homeothermic. Incubation means sea turtles are constrained to nest in at least subtropical climates: viviparous sea reptiles using the same method as D. woulf have no need to migrate in order to reproduce. I can't post in the comments so please direct him to this if you can.
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| Rodlox | Aug 22 2017, 11:02 PM Post #3 |
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Superhuman
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...it takes you four paragraphs to say. Naish provided at least as much detail as you are - I imagine its more, but some of his references went over my head. |
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.---------------------------------------------. Parts of the Cluster Worlds: "Marsupialless Australia" (what-if) & "Out on a Branch" (future evolution) & "The Earth under a still sun" (WIP) | |
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| LittleLazyLass | Aug 22 2017, 11:18 PM Post #4 |
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Proud quilt in a bag
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TetZoo articles aren't not ever were intended to be in-depth. They were always summaries or primers, bar cases where there's nothing to say on a subject except for a few paragraphs. |
totally not British, b-baka! You like me (Unlike)I don't even really like this song that much but the title is pretty relatable sometimes, I guess. Me What, you want me to tell you what these mean? Read First Words Maybe | |
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| kusanagi | Aug 23 2017, 03:18 AM Post #5 |
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Adolescent
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There's no need for me to provide depth, as I'm not writing an article and haven't for years. Just correcting a mistake and making observations: the Dermochelys-protostegid clade and what Hespertestudo tells us about large bodies and cold blood in cool climates. The error about the last meiolanids hunted to extinction by abos, at least needed correcting.
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| Fazaner | Aug 23 2017, 03:35 AM Post #6 |
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Шашава птичурина
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About the extinction of meiolanids, at least this species, but in more details.
And a question, when megalochelys atlas got extinct, what i find only give the crude estimate Pliocene or Pleistocene, although i might be a little nitpick now, i would like to know since that was relatively recent. |
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Projects (they are not dead, just updated realy slowly, feel free to comment): -World after plague After a horrible plague unleashed by man nature slowly recovers. Now 36 million years later we take a look at this weird and wonderful world. -Galaxy on fire. They have left their home to get out of war. They had no idea what awaits them. My Deviant art profile, if you're curious. Before you get offended or butthurt read this | |
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| kusanagi | Aug 23 2017, 03:55 AM Post #7 |
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Adolescent
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I had trouble finding extinction dates of tortoises: there is even a giant tortoise I found referenced as present on Taiwan, and extinct during the timeframe of H. sapiens settlement, but no details like, you know, the species. It doesn't help that testudinid taxonomy is historically a mess. But FWIW they follow the same extinction patterns as other hindgut fermenters: frequent turnover whereas ruminants and macropods are relatively immune. To my knowledge most Pleistocene giant tortoises never met H. sapiens, and there is even a paper I found summarising this. Lord Howe was unsettled before the 19th century. Whenever M. died out it was not anthropogenic, and I have seen the extinction listed as contemporaneous with the temporary extinction of the Aldabra giants. This may have been only a supposition but it is intuitive especially if you DO regard M. as an anthropogenic extinction elsewhere. https://www.jstor.org/stable/40287719?seq=1#page_scan_tab_contents |
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| Fazaner | Aug 23 2017, 04:21 AM Post #8 |
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Шашава птичурина
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Yeah, taxonomy can be a mess sometimes, and could the appearance of ice ages ,and climate change that fallowed, be what brought giant tortoises like megalochelus to extinction, maybe it was to much for them. And for second point, wrong island, species that i referenced ,and most likely Naish too, is from Efate island, not Lord Howe. |
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Projects (they are not dead, just updated realy slowly, feel free to comment): -World after plague After a horrible plague unleashed by man nature slowly recovers. Now 36 million years later we take a look at this weird and wonderful world. -Galaxy on fire. They have left their home to get out of war. They had no idea what awaits them. My Deviant art profile, if you're curious. Before you get offended or butthurt read this | |
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| kusanagi | Aug 23 2017, 04:27 AM Post #9 |
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Adolescent
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My understanding is pigs did in the island tortoises after Europeans arrived, more so than direct overexploitation. Lapita people took pigs so in the South Sea islands the extinction of meiolanids was likely related to pigs. (Doesn't explain Lord Howe though.) |
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You like me 
Just correcting a mistake and making observations: the Dermochelys-protostegid clade and what Hespertestudo tells us about large bodies and cold blood in cool climates. The error about the last meiolanids hunted to extinction by abos, at least needed correcting.


7:26 PM Jul 10