For the first time µCT scans expose Effigia in several views

From the Bestwick et al 2022 abstract:
“Here, we restore the skull morphology of Effigia, perform myological reconstructions, and apply finite element analysis to quantitavely investigate skull function. We infer that Effigia was a specialist herbivore that likely fed on softer plant material, a niche unique among the study taxa and potentially among contemporaneous Triassic herbivores.”

Among the LRT poposaurs
(Fig 3), Bestwick et al listed Shuvosaurus 1x, Lotosaurus 1x, Silesaurus 0x, Sacisaurus 0x, Poposaurus 1x and Turfanosuchus 0x. The authors reported, “Phylogenetic relationships within Poposauroidea are relatively well resolved.”

The ten authors are kidding themselves and short-changing their readers by excluding several poposaurs (listed above). In the LRT relationships are completely resolved by including taxa excluded by Bestwick et al. who borrowed an invalidated cladgoram from co-author Sterling Nesbitt 2011, who was working on his doctoral dissertation and publishing that as a paper eleven years ago.

It’s never a good idea to give big assignments like ‘examining all pertinent taxa’ to young doctoral students. Such young people have the least experience. Mistakes are inevitable. And then it gets worse. We’ve seen some mistakes promoted by professors intent on selling traditional, but outdated hypotheses published in their own university textbooks. Doctoral candidates are dependent on the judgement and bias of their mentor professor. So they have to do what they are told to do. It’s a feudal system designed to maintain that system and squelch unapproved discoveries.

Bestwick et al confessed,
“The order in in which poposaurid bauplans were assembled and/or modified is currently unclear (referencing co-author Nesbitt 2011),”

That study by Sterling Nesbitt was shown to suffer from inaccurate scoring to such an extent that when rescored here the topology matched the LRT.

Bestwick et al concluded,
“Effigia possesses an unusual mosaic of mechanical features that most likely restricted habitual feeding functions to the anterior portion of its jaws. A shearing motion between the anterior parts of the mandible and rostrum during orthal closure would generated the least stress under modeling conditions.”

“Shearing” is usually done with shears = scissors. Scissors require a tight rotating joint that permits cutting at the precise junction of two sharp surfaces brought into close contact. That’s not what we see here (Fig. 5). Instead the mandible is smaller than the rostrum making it extremely loose and mobile. Apparently this obvious key to the Effigia feeding apparatus was overlooked by all ten co-authors.

What is the tenth man rule?
“The Tenth Man strategy essentially says that if nine people agree on a particular course, the tenth person must, in the context of this strategy, take a contrary approach so that all alternatives can be considered. In business, this process can help break “groupthink” and ensure that a business considers all options.”

Effigia okeeffeae
(Nesbitt and Norell, 2006) 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 reassessment by Nesbitt and Norell (2006) and Nesbitt (2007) nested Effigia among the poposaurid rauisuchians based largely on the ankle, which they reported articulated in a crocodile-normal configuration, with a morphology similar to Alligator.

Yes, poposaurids are rauisuchians. For the same reason: crocodylomorphs and dinosaurs (including birds) are rauisuchians. They are all descendants of rauisuchians in the LRT (Fig 3).

Relying on ankle joints is no longer a paleo fad. The LRT employs 236 multi-state characters and 2100 taxa to determine tree topology and interrelationships.

This is yet one more reason why you need to build your own LRT, so you. too, can use this powerful tool with authority. Then, when you test your own wide gamut of taxa, you’ll have the confidence that taxon exclusion will not be your problem.

References
Bestwick J et al (9 co-authors) 2022. Cranial funtional morphology of the pseudosuchian Effigia and implications for its ecological role in the Triassic. AnatomyPubs. Special Issue Article. online
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