Talk:Ankylosauridae

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[edit] New phylogeny of Ankylosauridae

A new cladistic analysis by Hill et. al. (2003) shows Polacanthidae to be paraphyletic, with Gargoyleosaurus, Gastonia, Hoplitosaurus, Hylaeosaurus, Mymmorapelta, and Polacanthus placed in different steps between one another. It also places Minmi within Ankylosauridae, resolving the position of Minmi itself. The phylogeny of Ankylosauridae after Hill et. al. (2003) is shown here:

Ankylosauridae

|--Gargoyleosaurus
`--+--Gastonia
   `--+--Gobisaurus
      `--+--Minmi
         `--+--o Pinacosaurus
             `--+--Talarurus
                `--+--o Shamosaurinae
                   |  |--Shamosaurus
                   |  `--Tsagantegia 
                   `--o Ankylosaurinae
                      |--+--Tarchia 
                      |  `--Saichania
                      |--Tianzhenosaurus
                      |--Nodocephalosaurus
                      |--Shanxia
                      |--Ankylosaurus
                      `--Euoplocephalus

The ankylosaurid taxa not included in the cladistic analysis are Acanthopholis, Aletopelta, Amtosaurus, Bissektipelta, Cedarpelta, Crichtonsaurus, Glyptodontopelta, Hoplitosaurus, Hylaeosaurus, Maleevus, Mymoorapelta, Polacanthus, and Sauroplites.

This paper not only recognizes the validity of Shanxia and Tianzhenosaurus, but it also proves that Polacanthidae is an artificial, paraphyletic assemblage and should be abandoned.

Hill, R. V., Witmer, L. M. & Norell, M. A., 2003: A New Specimen of Pinacosaurus grangeri (Dinosauria: Ornithischia) from the Late Cretaceous of Mongolia: Ontogeny and Phylogeny of Ankylosaurs. American Museum Novitates: 3395, pp. 1-29.

Therefore, add Minmi to the Ankylosauridae and revise the relations of ankylosaurid genera by deleting Polacanthidae. The paper mentioned above once again corroborates the monophyly of an nodosaurid-ankylosaurid dichotomy. —The preceding unsigned comment was added by 72.194.116.63 (talk) 01:32, 24 December 2006 (UTC).

How exactly is it supposed to prove there is no Polacanthidae or Polacanthinae if it doesn't include Hylaeosaurus, Mymoorapelta, Hoplitosaurus, or, perhaps most importantly, Polacanthus? J. Spencer 16:11, 26 December 2006 (UTC)

Yes, by definition Polocanthidae/inae must include Polacanthus. Interpreting a study that doesn't include that genus in this way is original research (original speculation, actually), unless the author of that paper actually discusses Polacanthus or polacanthidae. Dinoguy2 18:54, 26 December 2006 (UTC)

The flaw to Hill et al, as well as Vickaryous et al (in the Dinosauria) is that the analyses are based ONLY on the skulls. I guess ankylosaurs had no bodies, but crawled along the ground using their tongues. As Carpenter noted in his phylogentic analysis, many of the key features in the polacanthids occurs in the postcrania. Anky-man 12:41, 19 March 2008 (UTC)

[edit] An Apparent Discrepancy

There is an apparent discrepancy that I’m unqualified to resolve. Page http://en.wikipedia.org/wiki/Ankylosauria says that Ankylosauria first appeared in the early Jurassic (“Ankylosauria is a group of herbivorous dinosaurs of the order Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony scutes, although many of them had other types of armor as well. Ankylosaurs were bulky quadrupeds, with short, powerful limbs. They are first known to have appeared in the early Jurassic Period of China”), but page http://en.wikipedia.org/wiki/Mymoorapelta says that one of the earliest known anklyosaurs appeared during the late Jurassic (“Mymoorapelta ("Shield of Mygatt-Moore") is an ankylosaur from the Late Jurassic (Kimmeridgian-Tithonian)…Along with Gargoyleosaurus pankinorum, Mymoorapelta is one of the earliest known ankylosaurs,”). When did they first appear, early Jurassic or late Jurassic?

Mike Sarles —Preceding unsigned comment added by 68.221.45.49 (talk) 16:49, 5 November 2007 (UTC)

It should be worded better, but the earliest known ankylosaurians are indeed from the Early Jurassic of China. However, Mymoorapelta and Gargoyleosaurus are in one sense among the earliest known ankylosaurians even though they are from the Late Jurassic of North America, because there aren't many ankylosaurians known from the Jurassic, and they were earlier than the great majority of ankylosaurians. This should be revised, though, as it can mislead. J. Spencer 18:06, 5 November 2007 (UTC)