Talk:Triconodonta
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Assessment comments
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Did they lay eggs?
- Since living monotremes lay eggs, I would think it's more likely that triconodonts also laid eggs if they split away from the main line of mammalian evolution before the monotremes did, and more likely that they didn't lay eggs if they split away after the monotremes. But don't quote me on that because, in the first place, there's no reason that I know of why triconodonts couldn't have evolved to be viviparous independently of marsupials and placentals; and, secondly, egg-laying might not have disappeared until after both monotremes and triconodonts had gone their separate ways. In other words, I don't know. And I'd be most interested if anybody does think they have the answer! Gnostrat 04:01, 10 September 2007 (UTC)
[edit] Define a mammal
Mathew5000 has asked me to have a look at this article, and I decided on some changes to address the following:
(1) Observing that "very few groups of non-Therian animals" (everything from sponges to symmetrodonts!) have any chance of being called mammals does seem to be stating the obvious. Just a little.
(2) "Many other extinct groups of Mesozoic mammals are now placed just outside Mammalia proper, at least according to the cladistic definition of the word "mammal"." First, there's a conflict between two usages of "mammal" within the same sentence. Secondly, most of the Mesozoic groups that have ever been classed as mammals are actually still classed as (crown-group) mammals under all of the current proposals. Finally, there's a lack of neutrality (no doubt unintentional) in describing one controversial proposal as the cladistic definition. Some groups are indeed no longer included in Mammalia by some cladists; it depends on who you read. We currently have at least three competing definitions of Mammalia: crown-group (the narrowest), traditional (equivalent to Mammaliaformes), and Benton's (=Mammaliaformes + Sinoconodon + Adelobasileus). But the way it was phrased here, you would think the crown-group approach had won the argument — the latest word in cladistics (there are no other worthwhile definitions than cladistic ones). And you wouldn't know any different if you only referred to the Mammalia and Mammaliaformes articles, either — those will also need fixing up at some stage. Gnostrat 04:01, 10 September 2007 (UTC)
