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Effigia palate and occiput
We looked at the poposaur Effigia earlier here and here. Having never attempted a reconstruction of the palate I do so here.
Figure 1. Effigia. is an odd derived poposaur with tiny hands and no teeth. In competition with dinosaurs, poplars did not fare as well. The dentary and predentary have been modified here from prior attempts to more closely match the mandible of Shuvosaurus (Fig. 3).
Effigia okeeffeae (Nesbitt and Norell 2006, Nesbitt 2007) Carnian, Late Triassic, ~210 mya, ~ 2 m in length, was originally considered an early theropod dinosaur by Colbert, who collected the specimen in the late 1940s but never removed it from its jacket. A recent reassessment by Nesbitt and Norell (2006) and Nesbitt (2007) nested Effigia among the poposauridis. It is an odd bipedal poposaur and perhaps the most derived member of a clade composed almost entirely of odd derived members. The reconstruction of the skull has been controversial. Perhaps only a direct tracing and shifting of the elements can solve this puzzle. All the pieces in the disarticulated fossil will come together precisely if they are correctly reassembled.
The palate
It is possible that the palatine (Fig. 2). was misidentified originally as the right ectopterygoid. If so, then the palate resembles that of known sister taxa, like Shuvosaurus (Fig. 3)..
Figure 2. Effigia palate in situ (left) and reconstructed by reassembling colored elements (at right).
Due to the long premaxilla
and the short maxilla the Effigia palate shifts most of the palatal elements into a smaller space. Even so all maintain their original and typical connections to the other skull elements.
Figure 3. Shuvosaurus, a sister to Effigia, has a similar palate in this reconstruction, but it was not reconstructed like this originally.
You really can’t talk about
the palate of Effigia without comparing it to its sister, Shuvosaurus (Fig. 3). Here the main triangular part of the pterygoid must be imagined, but the quadrate processes are present and quite robust. The palatines frame the internal nares posterior to the palatal processes of the maxilla and premaxilla.
Figure 4, the occiput of Effigia colorized here to segregate elements. That’s the central supraoccipital in pink flanked by two opisthotics in lavender, all displace dorsally. Originally they were framed by the squamosals in gold. Quadrates in red and basisphenoid in purple.
Effigia occiput
The above image (Fig. 4, Nesbitt 2007) is a CT scan of the Effigia occiput colorized to aid identification of the elements. The occiput is so inclined it is almost continuous with the palate. Originally the supraoccipital + opisthotics were identified as the two parietals with no median element recognized. Neither the supraocipital or the opisthotic were identified otherwise.
Effigia References
Nesbitt SJ and Norell MA 2006. Extreme convergence in the body plans of an early suchian (Archosauria) and ornithomimid dinosaurs (Theropoda). Proceedings of the Royal Society B 273:1045–1048. online
Nesbitt S 2007. The anatomy of Effigia okeeffeae (Archosauria, Suchia), theropod-like convergence, and the distribution of related taxa. Bulletin of the American Museum of Natural History, 302: 84 pp. online pdf
AMNH Effigia webpage
wiki/Effigia
Shuvosaurus References
Alcober O, Parrish JM. 1997. A new poposaurid from the upper Triassic of Argentina. Journal of Vertebrate Paleontology 17:548–556
Brusatte SL, Benton MJ, Desojo JB and Langer MC 2010. The higher-level phylogeny of Archosauria (Tetrapoda: Diapsida), Journal of Systematic Palaeontology, 8:1, 3-47.
Chatterjee S 1991. An unusual toothless archosaur from the Triassic of Texas: the world’s oldest ostrich dinosaur? Abstract, Journal of Vertebrate Paleontology, 8(3): 11A.
Chatterjee S 1993. Shuvosaurus, a new theropod: an unusual theropod dinosaur from the Triassic of Texas. National Geographic Research and Exploration 9 (3): 274–285.
Rauhut OWM 1997. On the cranial anatomy of Shuvosaurus inexpectatus (Dinosauria: Theropoda). In: Sachs, S., Rauhut, O. W. M. & Weigert, A. (eds) 1. Treffen der deutschsprachigen Palaeoherpetologen, Düsseldorf, 21.-23.02.1997; Extended Abstracts. Terra Nostra 7/97, pp. 17-21.
Long R and Murry P 1995. Late Triassic (Carnian-Norian) Tetrapods from the Southwestern United States. New Mexico Museum of Natural History and Science Bulletin 4, Pp. 153-163.
Source: https://pterosaurheresies.wordpress.com/2015/03/13/effigia-palate-and-occiput/
