Effigia palate and occiput

Updated March 13, 2015 with a new palate figure based on the photo, not the original drawing in Effigia and Shuvosaurus was modified in turn.

We looked at the poposaur Effigia earlier here and here. Having never attempted a reconstruction of the palate I do so here.

effigia588

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).

Figure 2. Effigia palate in situ (left) and reconstructed by reassembling colored elements (at right). Click to enlarge.

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.

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.

effigia-occiput588

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.

wiki/Shuvosaurus

 

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Marasuchus skull restored

Updated March 13 with text and figure corrections and overlooked references.

Very few skull bones are known for Marasuchus, the tiny theropod-like dinosaur or proto-dinosaur. Here’s a shot at a restoration of the skull (Fig. 1).

Figure 1. Marasuchus skull restored. My what big teeth you have! Based on the maxilla and occiput, this appears to be a long, low skull. Looks like a little basal theropod, like Tawa. Line drawing from Theropod Database in which M. Mortimer moved the 'quadrate' to the postorbital, based on Bonaparte 1975.

Figure 1. Marasuchus skull restored. My what big teeth you have! Based on the maxilla and occiput, this appears to be a long, low skull. Looks like a little basal theropod, like Tawa. Line drawing from Theropod Database in which M. Mortimer moved the ‘quadrate’ to the postorbital, based on Bonaparte 1975.

Marasuchus would make a pretty good little basal theropod/basal dinosaur EXCEPT,

  1. each cervical is too short
  2. no cervicals have epipophyses
  3. the pubis is too short
  4. and it has no boot
  5. the ischium is too deep and V-shaped along its entire length.
  6. the femur lacks some grooves and bumps found in sister taxa
  7. the proximal tibia has a lateral bump does not reach the posterior rim
  8. distal tarsal 4 is not flat
  9. the astragalus has a larger facet for a larger fibula

Marasuchus is also smaller than basal dinosaur/theropod sisters (Fig. 2) and, considering this list, one wonders if some of these traits are due to neotony, the juvenilization of traits when a taxon experiences generational miniaturization.

Figure 1. To scale compared to Marasuchus, Agnosphitys cromhallensis (Fraser et al. 2002) is known from a selection of uncrushed bones, all of which resemble those from Marasuchus, but slightly larger with a relatively longer rostrum and shorter arms. These two represent a separate and distinct lineage of theropods.  Click to enlarge.

Figure 2. To scale compared to Marasuchus, Agnosphitys cromhallensis (Fraser et al. 2002) is known from a selection of uncrushed bones, all of which resemble those from Marasuchus, but slightly larger with shorter arms. These two represent a separate and distinct lineage of theropods.  Click to enlarge.

If not as a basal theropod close to the odd theropods, Procompsognathus and Segisaurus, then where else could Marasuchus more parsimoniously nest? Most of the above traits can be found individually far from bipedal dino-types, but the suite cannot be found elsewhere. I think we have to rely on maximum parsimony here.

Your thoughts?

References
Bonaparte JF 1975. Nuevos materiales de Lagosuchus talampayensis Romer (Thecodontia – Pseudosuchia) y su significado en el origen de los Saurischia, Chañarense Inferior, Triasico Medio de Argentina [New materials of Lagosuchus talampayensis Romer (Thecodontia – Pseudosuchia) and its significance on the origin of the Saurischia, Lower Chañares, Middle Triassic of Argentina]. Acta Geológica Lilloana 13:5-90.
Romer AS 1971. The Chanares (Argentina) Triassic reptile fauna X. Two new but incompletely known long-limbed pseudosuchians: Brevoria 378: 1-10.
Romer AS 1972. The Chanares (Argentina) Triassic reptile fauna. XV. Further remains of the thecodonts Lagerpeton and Lagosuchus: Breviora 394: 1-7.
Sereno PC and Arcucci AB 1994. Dinosaurian precursors from the Middle Triassic of Argentina: Marasuchus lilloensis gen. nov. Journal of Vertebrate Paleontology, 14: 53-73

Theropod Database

wiki/Marasuchus

Not Arizonasaurus, but Postosuchus, made the giant Isochirotherium tracks

A recent paper by Diedrich (2015) purported to match the Arizonasaurus to giant Isochirotherium tracks from the Middle Triassic of Germany (Fig. 1).

The problem is,
no manus or pes are known for Arizonasaurus. Furthermore, all related taxa in the large reptile tree have digit 3 the longest, and all digits are elongate. The giant Isochirotherium tracks indicate that both digits 2 and 3 are the longest, and they are short. So matching candidates have to be found elsewhere, not close to Arizonoasaurus (although the size and time are right!).

Among the 504 taxa in the large reptile tree that are possible candidates with digits 2 and 3 the longest are Erythrosuchus (Fig. 1), Shansisuchus, Lotosaurus and the Postosuchus alisonae (Peyer 2008, Fig. 1). It turns out that only the latter is the best match when scaled up to the size of P. kirkpatrchicki (Chatterjee 1985, Fig. 1).

Figure 1. Giant Isochirotherium tracks matched to Postosuchus alisonae scaled up to the size of P. kirkpatrcki.

Figure 1. Giant Isochirotherium tracks matched to Postosuchus alisonae scaled up to the size of P. kirkpatrcki. Click to enlarge. This taxon was not considered originally because it is Late Triassic and the tracks are Middle Triassic.

Postosuchus was not mentioned in the text
because Diedrich (recent email) knew Postosuchus was Late Triassic, not Middle Triassic. He did not accept the idea that between the origin, radiation and extinction of Postosuchus there might have been a Middle Triassic relative.

Diedrich also saw the small manus tracks and assumed they were produced by a large poposaurid. Unfortunately, Arizonasaurus does not nest with poposaurids either. And poposaurids, other than Lotosaurus, do not match the track morphology.

It would have been helpful,
I suppose, to do what I did and make a list of possible candidates from a large list, AND THEN delete the possible candidates one by one as bad matches. Other than that phylogenetic bracketing mismatch, Diedrich does good work with excellent graphics. It took a leap of faith, I suppose to match tracks to a taxon for which no manus or foot is known.

C. Diedrich writes:
“Watch my ARTE docu – there you see Arizonasaurus (Ticinosuchus and Macrocnemus) walking in my point of view combining trak/sleketal records”:http://www.youtube.com/watch?v=b9GcVmb6OtE

References
Chatterjee S 1985. Postosuchus, a new Thecodontian reptile from the Triassic of Texas and the origin of Tyrannosaurs. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences 309 (1139): 395–460. doi:10.1098/rstb.1985.0092.
Diedrich C 2015.
Isochirotherium trackways, their possible trackmakers (?Arizonasaurus): intercontinental giant archosaur migrations in the Middle Triassic tsunami-influenced carbonate intertidal mud flats of the European Germanic Basin  Carbonates and Evaporites  DOI 10.1007/s13146-014-0228-z
Novak SE 2004. A new specimen of Postosuchus from the Late Triassic Coelophysis Quarry, siltstone member, Chinle Formation, Ghost Ranch, New Mexico. M.S. thesis, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
Peyer K Carter, JG, Sues H-D, Novak SE, and Olsen PE 2008. A new Suchian Archosaur from the Upper Triassic of North Carolina. Journal of Vertebrate Paleontology 28 (2): 363–381. doi:10.1671/0272-4634(2008)28[363:ANSAFT]2.0.CO;2.

The evolution of the Sordes wing and uropatagia: 1971 to 2011

When insect-specialist, A. Sharov (1971),
first traced the wings of the Sordes holotype (PIN 2585/3) he considered every soft tissue on the specimen some sort of wing membrane with little to no taphonomic displacement (Fig. 1c). Sharov added a skull where there should have been one. He attached the wings to the ankles and considered a V-shaped dark patch the trailing edge of a single uropatagium stretched between the hind limbs (detached from the tail, framed and controlled at least in part by pedal digit 5). Such a structure had never been seen before on any pterosaur.

Sharov also traced large puffs of soft tissue anterior to the right free fingers and lateral to the left ankle (Fig. 1c). These have been ignored ever since.

Unwin and Bakhurina (1994)
echoed Sharov’s observations in an international publication, Nature (Fig. 1d), focusing on the membrane attachment to the ankles and the uropatagium stretching between them and the lateral toes, already extremely bent as in most basal pterosaurs. Unfortunately, less data, rather than more, was presented. And pterosaur workers were left scratching their heads. How does an embryo develop a membrane between the two hind limbs and not attach to the tail (as in bats)? Was the cloaca above or below this membrane? How could a pterosaur walk bound like this? How could it fly bound like this?

Figure 4. Sordes wing drift hypothesis from Peters (2002) which attempted to show that the wings and uropatagia of Sordes were more like those of other pterosaurs than the other way around. The very deep uropatagia are misinterpretations prior to the realization that the left brachiopatagium (main wing membrane) was displaced to the ankle area.

Figure 1. Sordes wing drift hypothesis from Peters (2002) which attempted to show that the wings and uropatagia of Sordes were more like those of other pterosaurs than the other way around. Unfortunately the very deep and hairy uropatagia are misinterpretations prior to the realization that the left brachiopatagium (main wing membrane) was displaced to the ankle area (Figure 3). Click to enlarge.

Peters (1995)
suggested that some elements of Sordes had taphonomically drifted. Moving the elements back to their purported in vivo positions created a morphology more like that of all other pterosaurs. Unfortunately some identification mistakes were made due to inexperience and working with low resolution second hand data, but further work demonstrates the basic idea of taphonomic shifting was sound.

Figure 1. Sordes interpreted by me in Nature 1995. At that time. remember, no one had ever heard of a uropatagium. And the purported "fact" that this flap of skin spanned the hind limbs without connecting to the tail seemed pretty hard to swallow for a majority of paleontologists. The only images available were small and indistinct. Even so, an attempt was made here to understand the taphonomy of the specimen and how it came to sport such a strange autapomorphy that has not been seen since on any pterosaur fossil. Despite the sincerity of this effort, it includes several mistakes rectified now in ReptileEvolution.com/sordes.htm after publication of the specimen in a larger format with higher resolution.

Figure 2. Sordes reinterpreted by Peters (1995). Since no other pterosaur had such a wing and uropatagium plan as Sharov had proposed and Unwin and Bakhurina echoed, I assumed the parts had taphonomically drifted from their in vivo positions. I was largely correct but some mistake were made. The V-shaped patch between the ankles actually is part of the left wing, not the right one, which is undisturbed in the fossil. And what everyone thought was the skull is actually the left hand and m4.1.

Peters (2002)
refigured the Sordes wing (Fig. 1a, b, e), this time attributing certain odd alignments to matrix planes and taphonomic shifting. This was part of a larger study examining a wide range of pterosaur wing plans. Unfortunately, the uropatagia were again incorrectly interpreted, this time as uropatagia that had overlapped medially during taphonomy. The purported skull was ignored.

ReptileEvolution.com (Peters 2011)
offered a new interpretation that identified bones thought to have been the skull roof as left manual 4.1 (Fig. 3). Bones thought had been considered facial bones were reidentified as the free fingers and metacarpus, somewhat busted up. In one of those wonders of taphonomic displacement, in this fossil it appears that manual 4.1 was joined to the distal left humerus,! This left the radius and ulna unaccounted for. And there’s our solution!

The myth of the pterosaur uropatagium

Figure 3. The Sordes uropatagium is actually displaced wing material towed to the ankles by the displaced radius and ulna.

Impressions of the ulna and radius (click here for rollover image) were identified near the left ankle. These formed the straight lines that were thought by previous authors to be the straight trailing edge of an undamaged wing membrane (Sharov 1971, Unwin and Bakhurina 1994). Unfortunately no prior workers raised the question: how could the trailing edge be taut straight when relaxed?

However, it is interesting to note in figure 1 that the tracings of this area made by Sharov (1971) and Unwin and Bakurina (1994) do not match. What were they each looking at?

In the Sordes holotype, along with the displaced ulna and radius came a large chunk of wing membrane, now detached, folded upon itself like a ribbon and spanning the ankles, giving the illusion of a uropatagium trailing edge. Note that no trace of this purported uropatagium exists close in to the femora. Instead faint impressions of the twin uropatagia, identical to those of other pterosaurs and Sharovipteryx, are faintly preserved behind each knee.

Figure 5. Sordes from Elgin, Hone and Frey 2011. While we were all hoping for more detail, we got less.

Figure 4. Sordes from Elgin, Hone and Frey 2011. While we were all hoping for more detail, we got less.

Elgin, Hone and Frey 2011
published a tracing of Sordes, repeating Sharov’s original interpretation, assuming that little to no taphonomic displacement took place (Fig. 4). Based on the left wing membrane trailing edge, this seems to have been traced from Unwin and Bakhurina 1994 (Fig. 1c, more details and links below) rather than Sharov (1971).

Very few pterosaurs are perfect specimens
Prior workers, even after noticing the back-turned cervicals of Sordes, the lack of a skull with identifiable features and the apparent loss of the left free fingers together with m4.1 (originally misidentified as an in-place radius and ulna, Fig. 1c), did not consider the possibility of taphonomic displacement. Nor did they attempt to more accurately trace the skeleton and soft tissue since 1971(!). Nor did they attempt to reconcile the soft tissues of Sordes with those of other pterosaurs, except when Elgin, Hone and Frey (2011) attempted the exact opposite (details and data here and here) with even less detail to their tracings (Fig. 4) than Unwin and Bakhurina (1994)! They explained away all the other wing differences to fit the Sordes model and NOT with greater precision.

Unfortunately
most pterosaur workers (e.g. Unwin 2005; Elgin, Hone and Frey 2011; Witton 2013) continue to reconstruct their pterosaurs with deep chord wing membranes in blind accord with Sharov (1971) rather than changing the Sordes wing to match that of all other pterosaurs (more here on that topic). They argued that the Zittel wing must have been trimmed or must have extended to the ankles. They argued that the Vienna specimen of Pterodactylus (Fig. 4) likewise must have had wings attached to the ankles, when they clearly do not, and explained away the difference with the term, “shrinkage.”

The Vienna Pterodactylus.

Figure 5. The Vienna Pterodactylus. Click to animate. Wing membranes in situ (when folded) then animated to extend them. Contra Elgin, Hone and Frey (2011) there is no shrinkage here or in ANY pterosaur wing membrane. There is only an “explanation” to maintain the Sordes deep chord wing hypothesis when it is the Sordes wing that needs to conform to this very clear data.

If you think this defies all logic,
I agree with you. And yet, it continues…

References
Elgin RA, Hone DWE and Frey E 2011. The extent of the pterosaur flight membrane. Acta Palaeonntologica Polonica 56(1): 99-111.
Peters, D. 1995. Wing shape in pterosaurs. Nature 374, 315-316.
Peters D 2002. A New Model for the Evolution of the Pterosaur Wing – with a twist. Historical Biology 15: 277–301.
Sharov AG 1971. New flying reptiles from the Mesozoic of Kazakhstan and Kirghizia. – Transactions of the Paleontological Institute, Akademia Nauk, USSR, Moscow, 130: 104–113 [in Russian].
Unwin, D. M. 2005. The Pterosaurs fromDeep Time. Pi Press, New York, 347 pp.
Unwin DM and Bakhurina NN 1994. Sordes pilosus and the nature of the pterosaur flight apparatus. Nature 371: 62-64.
Witton M. 2013. Pterosaurs. Princeton University Press. 291 pages.

wiki/Sordes

How one Sordes evolved into Dorygnathus via Cacibupteryx

I have seen images of three
more or less complete Sordes (Sharov 1971, Oxfordian/Kimmeridgian) specimens (Figs. 1-3). Unfortunately only the holotype PIN 2585/3 (Fig.1) was described (Sharov 1971). Later Unwin and Bakhurina (1994) echoed Sharov’s findings, that Sordes had wing membranes attached to the legs and another membrane (uropatagium) between the legs, but their tracings were, at best, outlines. No one else who has actually seen this taxon has further described the holotype in more detail with precise tracings.  And it’s been almost 45 years!

Figure 2. Sordes holotype, PIN 2585/3. Soft tissue in abundance, but the skull is largely gone.

Figure 1. Sordes holotype, PIN 2585/3. Soft tissue in abundance, but the skull is largely gone.

The Sordes paratype PIN 2470/1 (Fig. 2) includes a fish and lots of hair. (Unwin 2006 reports that nine specimens of Sordes were found in the 1960s), all undescribed at present.

Figure 4. The third Sordes specimen PIN number unknown. That is a small fish in the middle. Lots of soft tissue here.

Figure 2. The paratype of Sordes specimen PIN 2470/1). That is a small fish in the middle. Lots of soft tissue here.

A third specimen
of Sordes (PIN 2585-25) is also well known and shows the skull in lateral view. Soft tissue is present here, but much less extensive. Even less well known are the five or six other specimens (among them: PIN 104/73, PIN 2585/36, PIN 2585/37) Are they just bits and pieces? Does anyone know? Are they published anywhere? I have a note into the PIN for more info, but so far no reply.

Figure 2. The PIN 2585-25 specimen of Sordes.

Figure 3. A third specimen of Sordes, PIN 2585-25.

The three specimens have all been identified as Sordes, but they nest in three distinct nodes on the large pterosaur tree, phylogenetically closer to other taxa than to each other (Fig. 4).

Figure 4. The three Sordes specimens to scale. They are close, but not identical. Shown above each is a closer sister taxon.

Figure 4. The three Sordes specimens to scale. They are close, but not identical. Shown above each is a closer sister taxon. Click to enlarge.

The Cacibupteryx connection
Cacibupteryx caribensisi (Gasparini, Fernández, and de la Fuente, 2004) Oxfordian, Late Jurassic ~160 mya was considered a rhamphorhychid and a scaphognathid, but it nests as a very basal dorygnathid. Derived from a sister to SordesCacibupteryx phylogenetically preceded all specimens of Dorygnathus.

Figure 4. Cacibupteryx to scale with the 2585/36 specimen attributed to Sordes. These two nest together in the large pterosaur tree.

Figure 5. Cacibupteryx ( IGO-V 208) to scale with the 2585/36 specimen attributed to Sordes. These two nest together in the large pterosaur tree, not quite with Sordes. These two were contemporaries, both from the Tropic of Capricorn, not a world apart, as they are now, but part of the supercontinent Pangaea prior to the appearance of the North Atlantic.

The Jianchangopterus connection
The holotype of Sordes (Fig. 4) nests with Jianchangopterus, at the the base of Pterorhynchus + the Wukongopteridae not far from the base of Scaphognathus and its many descendants. So with one Sordes at the base of all dorygnathids and one Sordes near the base of all scaphognathids, that means Sordes is the last common ancestor of all pterodactyloid-grade pterosaurs in the large pterosaur tree — still pretty far from any pterodactyloid-grade pterosaurs, which had four separate origins.

One wonders
why the other six specimens of Sordes have not been released. Are they just scraps? It’s been fifty years since their discovery. It’s time those specimens were presented and all three Sordes specimens were reintroduced in an academic publication. Since the three well-preserved specimens attributed to Sordes nest close to one another, but are not conspecific or even congeneric on the cladogram. doubt may be cast on the identity of the remaining specimens. We’ll have to see…

References
Cheng X, Wang X-L, Jiang S-X and Kellner AWA 2012. A new scaphognathid pterosaur from western Liaoning, China. Historical Biology iFirst article available online 29 Nov 2011, 1-11. doi:10.1080/08912963.2011.635423
Gasparini, Z, Fernández M and de la Fuente M 2004. A new pterosaur from the Jurassic of Cuba. Palaeontology 47(4): 919–927. doi:10.1111/j.0031-0239.2004.00399
Sharov AG 1971. New flying reptiles from the Mesozoic of Kazakhstan and Kirghizia. – Transactions of the Paleontological Institute, Akademia Nauk, USSR, Moscow, 130: 104–113 [in Russian].
Unwin DM and Bakhurina NN 1994. Sordes pilosus and the nature of the pterosaur flight apparatus. Nature 371: 62-64.
Zhou C-F 2014. Cranial morphology of a Scaphognathus-like pterosaur, Jianchangnathus robustus, based on a new fossil from the Tiaojishan Formation of western Liaoning, China. Journal of Vertebrate Paleontology 34(3):597-605.

wiki/Jianchangnathus
wiki/Cacibupteryx
wiki/Sordes

Another bad Quetzalcoatlus on YouTube

This YouTube video probably goes back a few years because Alan Turner looks quite young and the dear departed Larry Martin looks quite healthy.

Figure 1. Bad Quetzalcoatlus folds its wings transversely instead of posteriorly -- among many other faults.

Figure 1. Bad Quetzalcoatlus folds its wings transversely instead of posteriorly — among many other faults. Click to play video. Computer animators — please check online for your data! Don’t use Marx toys (Fig. 3)!

 

Figure 1. Quetzalcoatlus specimens to scale.

Figure 2. Quetzalcoatlus specimens to scale. It stood more like a giant stork. And the wings folded up posteriorly, essentially hiding the wing membrane.

 

Toy Pteranodon, ca. 1962, from the Marx Company.

Figure 3. Toy Pteranodon, ca. 1962, from the Marx Company.

Here’s the Marx toy Pteranodon (Fig. 3) that apparently served as the model for the documentary Quetzalcoatlus.

Pterosaurs have been maligned too often, and too often by experts. Let’s hope such foolishness stops sooner, rather than later.

 

Daemonosaurus cervicals and the recurring problem of taxon exclusion

Updated March 9, 2015 with the note that Sues et al. did not use suprageneric data,as reported earlier.. The supplemental data shows that several ornithischians were employed. I spent the day yesterday making the SuppData computer friendly and am today reviewing the scorings. I see several typos and reinterpretations. A later post will present both nexus files. 

Earlier we looked at the palate and occiput of Daemonosaurus Today we’ll reexamine the cervicals and update some notes.

Little noticed and poorly preserved,
the cervicals of the basal phytodinosaur, Daemonosaurus (Sues et al. 2011, CM 76821, Carnegie Museum of Natural History, Late Triassic) appear curiously small and elongated relatively to the tall, narrow skull (Fig. 1).

Figure 1. Daemonosaurus cervicals traced from in situ fossils and compared to sister taxa, Eoraptor, Leyesaurus, Heterodontosaurus and Pisanosaurus. Among these taxa, Daemonosaurus has the largest skull and most gracile cervicals. Click to enlarge.

Figure 1. Daemonosaurus cervicals traced from in situ fossils and compared to sister taxa, Eoraptor, Leyesaurus, Heterodontosaurus and Pisanosaurus. Among these taxa, Daemonosaurus has the largest skull and most gracile cervicals. Daemonosaurus likely had four more cervicals than preserved.

If the cervicals have been correctly traced
then, compared to sister taxa, Daemonosaurus has the largest skull relative to the most gracile cervicals. And there were likely four and a half more cervicals that were not preserved.

The cervicals are long, like those of basal sauropodomorphs, but the skull is tall, short and narrow, like those of basal ornithischians, like Heterodontosaurus. Overall the imagined body of Daemonosaurus was larger than all sister taxa except Leyesaurus, which had a longer neck. Note the similarities of Daemonosaurus to Pisanosaurus, which had much shorter cervicals, but was more closely related to other ornithischians, and to Dryosaurus, which also had shorter cervicals and no premaxillary teeth, but otherwise rather similar in morphology.

Here’s where Sues et al. 2011 differ from the large reptile tree
Sues et al. 2011 found Ornithischia and Sauropodomorpha branched off prior to Herrerasaurus. In  the large reptile tree they both branched off close to Eoraptor (which confirms sauropodomorph affinities according to Sereno et al. 2013) and Daemonosaurus is a basal ornithischian. Using the Sues et al. taxa (Fig. 2 and deleting all sauropodomorphs and ornithischians) the large reptile tree recovers the same tree topology. Different than I thought when this blogpost was first published, Sues et al. 2014 used genus-based taxa. A review of their work is in progress, but since they used Nesbitt 2011 for their database, I found several problems and strange-bedfellows earlier.

Figure 4. Daemonosaurus tree from Sues et al. 2014. Their one mistake was assuming sauropods and ornithischians branched off prior to Herrerasaurus. The large reptile tree has these clades branching off after Eoraptor. Delete those suprageneric clades and the tree recovered here matches the large reptile tree with similar deletions.

Figure 2. Daemonosaurus tree from Sues et al. 2014. Their one mistake was assuming sauropods and ornithischians branched off prior to Herrerasaurus. The large reptile tree has these clades branching off after Eoraptor. Delete those suprageneric clades and the tree recovered here matches the large reptile tree with similar deletions.

Daemonosaurus diagnosis (with my additions in color).
“Distinguished by the following unique combination of characters: skull proportionately deep and narrow (like Jeholosaurus, Heterodontosaurus = J, H), with short antorbital region (like J, H); premaxillary and anterior maxillary teeth much enlarged relative to more posterior maxillary teeth (like J, H)prefrontal large and occupies about 50 per cent of the dorsal margin of the orbit (like J, H); ventral process of lacrimal with slender posterior projection extending along anterodorsal margin of jugal (cannot confirm, this may be part of the jugal); dorsoventrally deep jugal with prominent lateral ridge (like H); postorbital with anterolateral overhang over orbit (like J, H); first two dentary teeth large and procumbent (like J, H); alveolar margin of dentary downturned at symphysis (like J, H); and third cervical vertebra with deep, rimmed, ovoid pleurocoel on the anterolateral surfaces of both centrum and neural arch (hard to see). Possible autapomorphies of Daemonosaurus include long posterior process of premaxilla that almost contacts anterior process of lacrimal (like J, H); and antorbital fenestra nearly the same size as external naris (like J, H);.”

It’s too bad
these authors missed this big, I mean really big discovery (the basalmost ornithischian!) due to their use of supragreneric taxa, false assumptions and taxon exclusion. It is also puzzling that no one since 2011 has raised their hand about these issues, except yours truly. Come on people, now that we know the problem, let’s fix this!

So, these questions pop up:
did the Ornithischia inherit short cervicals directly from a sister to Eoraptor? Or did basal phytodinosaurs enjoy a brief fling with elongate cervicals, as in the intervening sauropodomorphs — AND as demonstrated by Daemonosaurus? Or did Daemonosaurus independently elongate its cervicals?

That’s the frustration, joy and mystery of incomplete fossils.

PS Good news! Just heard Hans Sues and Sterling Nesbitt are working on a detailed description of Daemonosaurus.

References

Nesbitt SJ 2011. The early evolution of archosaurs: relationships and the origin of major clades. Bulletin of the American Museum of Natural History 352: 292 pp.
Sereno PC, Martínez RN and Alcober OA 2013. Osteology of Eoraptor lunensis (Dinosauria, Sauropodomorpha). Journal of Vertebrate Paleontology Memoir 12:83-179.
Sues H-D, Nesbitt SJ, Berman DS and Henrici AC 2011. 
A late-surviving basal theropod dinosaur from the latest Triassic of North America. Proceedings of the Royal Society Bpublished online