Halszkaraptor: what a story!

Published in Nature today
a Mongolian Late Cretaceous theropod that was rescued from the black market! It is supposed to be aquatic… but is it?

Figure 1. Halszkaraptor escuillei was originally considered an aquatic basal dromaosaur, but here nests with Shuvuuia, a sprinting biped.

Figure 1. Halszkaraptor escuillei was originally considered an aquatic basal dromaosaur, but here nests with Shuvuuia, a sprinting biped. It might not have been this chubby in the torso. All art is from Cau et al. 2017.

Halszkaraptor escuilliei (Cau et al. 2017; Late Cretaceous, Fig. 1) was originally considered an aquatic basal dromaeosaur related to Mahakala, but here Halszkaraptor nests with ShuvuuiaHaplocheirus and other non-aquatic sprinting dromaeosaurids. Manual digit 3 was the longest, but the thumb had the largest claw. The naris was displaced posteriorly. The fossil is preserved in 3D, largely articulated.

Figure 1. Shuvuuia and Mononykus to scale in various poses. The odd digit 1 forelimb claws appear to be retained for clasping medial cylinders, like tree trunks. The forelimb is very strong. Perhaps these taxa rest vertically and run horizontally. Click to enlarge.

Figure 2. Shuvuuia and Mononykus to scale in various poses. The odd digit 1 forelimb claws appear to be retained for clasping medial cylinders, like tree trunks. The forelimb is very strong. Perhaps these taxa rest vertically and run horizontally. Click to enlarge.

The Cau et al. cladogram
has many more bird-like theropods than the LRT. The taxa that nest together with Halszkaraptor in the LRT are sprinkled throughout the Cau et al. cladogram. In fact, all of the theropods that the two cladograms have in common nest in completely different nodes and leaves, except Haplocheirus nests in the same clade as Shuvuuia in both trees. Is this a case of taxon exclusion on the part of the LRT? Or just what happens when you score different traits? No reconstructions of sister taxa were provided.

FIgure 2. Subset of the LRT focusing on pre-bird theropods.

FIgure 2. Subset of the LRT focusing on pre-bird theropods. The taxa in the Velociraptor clade are sprinkled throughout the Cau et al. cladogram of theropods.

Let’s look at the pertinent parts of the Cau et al. abstract:
“Propagation X-ray phase-contrast synchrotron microtomography of a well-preserved maniraptoran from Mongolia, still partially embedded in the rock matrix, revealed a mosaic of features, most of them absent among non-avian maniraptorans but shared by reptilian and avian groups with aquatic or semiaquatic ecologies.

“This new theropod, Halszkaraptor escuillieigen. et sp. nov., is related to other enigmatic Late Cretaceous maniraptorans from Mongolia in a novel clade at the root of Dromaeosauridae. This lineage adds an amphibious ecomorphology to those evolved by maniraptorans: it acquired a predatory mode that relied mainly on neck hyperelongation for food procurement, it coupled the obligatory bipedalism of theropods with forelimb proportions that may support a swimming function, and it developed postural adaptations convergent with short-tailed birds.”
What about this theropod screams, “I’m aquatic!!” ?? This is one I just don’t see.
In the LRT
Halszkaraptor does not nest with other aquatic taxa. The neck is not particularly long compared to coeval Mononykus (Fig. 2), which has never been considered aquatic. The skull is very much like that of coeval Shuvuuia
Described in the press
as one of the oddest fossil yet found. This adjective usually gets attached to errors in identification. Halszkaraptor is not that odd. NatGeo reports, “Like modern aquatic predators, this dinosaur’s face seems to have had an exquisite sense of touch, useful for finding prey in murky waters. Its small teeth would have helped it nab tiny fish, and its limber backbone and flipper-like forelimbs suggest that it cut through the water with ease.”
This added later:
Apparently others have also seen the Shuvuuia connection. Author Andrea Cau listed 25 traits here that distinguish Halszkaraptor from Shuvuuia, but are found in dromaeosaurids. Perhaps this could all be cleared up easily, because in the LRT, Shuvuuia IS also a dromaeosaurid, not a distantly related theropod, as it nests in Cau et al. 2017.

References
Cau A, et al. 2017. Synchrotron scanning reveals amphibious ecomorphology in a new clade of bird-like dinosaurs. Nature. doi:10.1038/nature24679

wiki/Halszkaraptor
wiki/Shuvuuia

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Dinosaur outgroup taxon: Turfanosuchus

It was the Middle Triassic when
a sister to Turfanosuchus evolved into the basalmost dinosaur, Herrerasaurus (Figs. 1, 2)

Figure 1. Turfanosuchus compared to Herrerasaurus, the basalmost dinosaur.

Figure 1. Turfanosuchus compared to Herrerasaurus, the basalmost dinosaur. Lower image to scale.

Figure 2. Skull of Turfanosuchus compared to Herrerasaurus, the basalmost dinosaur.

Figure 2. Skull of Turfanosuchus compared to Herrerasaurus, the basalmost dinosaur.

Quick one today.
I’ll let the pictures tell the story…

References
Novas FE 1994. New information on the systematics and postcranial skeleton of Herrerasaurus ischigualastensis (Theropoda: Herrerasauridae) from the Ischigualasto
Reig OA 1963. La presencia de dinosaurios saurisquios en los “Estratos de Ischigualasto” (Mesotriásico Superior) de las provincias de San Juan y La Rioja (República Argentina). Ameghiniana 3: 3-20.
Sereno PC and Novas FE 1993. The skull and neck of the basal theropod Herrerasaurusischigualastensis. Journal of Vertebrate Paleontology 13: 451-476. doi:10.1080/02724634.1994.10011525.
Young CC 1973. [On a new pseudosuchian from Turfan, Sinking (Xinjiang).] Memoirs of the Institute of Vertebrate Paleontology and Paleoanthropology of the Academia Sinica, Series B 10:15-37.

wiki/Herrerasaurus
wiki/Turfanosuchus

The joy of finding mistakes: fewer stem dinosaurs

Finding mistakes is what I hope to do every day
in my own work, as well as that of others. Each time that happens, the data set improves. Lumping and splitting improves. The hypothetical topology of the large reptile tree (LRT, 1036 taxa) gets closer to echoing the topology of Nature itself. Science is a process of winnowing through the data and finding earlier mistakes.

Figure 1. Revision to the LRT with a focus on the Archosauria. Here taxa with a long carpus all nest within the Crocodylomorpha, following traditional thinking. Dinosaur outgroups are reduced. PVL 4597 is still the basalmost archosaur.

Figure 1. Revision to the LRT with a focus on the Archosauria. Here taxa with a long carpus all nest within the Crocodylomorpha, following traditional thinking. Dinosaur outgroups are reduced. PVL 4597 is still the basalmost archosaur.

Today
I discovered some scoring errors among former ‘stem dinosaurs’ that turned them into basal crocodylomorphs. That’s a small shift and it involved turning some ‘absent’ scores in pedal digit 5 to ‘unknown’. It’s noteworthy that some related taxa have two tiny phalanges on pedal digit 5. A related taxon, Gracilisuchu, was illustrated by Romer (1972, Fig. 3) as a combination or chimaera of separate specimens, something I just today realized and rescored. One of those specimens is the so-called Tucuman specimen (PVL 4597, Fig 1), which nests apart from the Gracilisuchus holotype (Fig. 2) in the LRT.

Figure 1. The PVL 4597 specimen attributed to Gracilisuchus by Lecuona et al. 2017, but nesting at the base of the Dinosauria in the LRT.

Figure 2. The PVL 4597 specimen attributed to Gracilisuchus by Lecuona et al. 2017, but nesting at the base of the Dinosauria in the LRT. That fibula flange turns out to be another important trait. 

The corrected results
resolve the long proximal carpal issue in crocodylomorphs very neatly. Now, as in traditional thinking, that trait is restricted to only the crocodylomorphs and it gives us a basalmost taxon with the trait, Junggarsuchus. You might think, and it would be reasonable to do so, that phylogenetic bracketing permitted the addition of a long carpus and long coracoids with more confidence to taxa that don’t preserve this, like Gracilisuchus and Saltopus. But another related basal crocodylomorph, Scleromochlus, has small round coracoids, evidently a reversal. The carpal length is not clearly documented in Scleromochlus (Fig. 4).

Gracilisuchus

Figure 3. A basal archosaur with a very similar nasal bone, Gracilisuchus. Note pedal digit 5 here. This is how Romer 1972 illustrated it. The actual data is shown in figure 2, the Tucuman specimen, PVL 4597. The coracoid is not known in the holotype. 

Despite the short round coracoids of Scleromochlu
and its apparently short carpals, enough traits remain to nest it as a basal crocodylomorph, following the rules of maximum parsimony.

Figure 1. Scleromochlus forequarters. The yellow area shows the hand enlarged in situ. The size of the Scleromochlus hand makes it the last possible sister to pterosaurs, famous for their very large hands.

Figure 4. Scleromochlus forequarters. The yellow area shows the hand enlarged in situ. Large carpals do not appear to be present and the coracoids are not elongated. 

On a more personal note
I found out my art and a short bio were included in a paleoart website:
http://paleoartistry.webs.com while looking for information on friend and paleoartist, Mark Hallett, (wikipage here) whose website is down and I worried about his health. No worries. Mark just let his website lapse.

The author of the paleoartistry page
had both kind words and controversy for me:
“After David Peters’ excellent paintings in Giants, and A Gallery of Dinosaurs and Other Early Reptiles, as well as his own calendar, it seemed he was on his way to becoming one of the most reliable paleoartists of the 1990s, if not of all time. However, very controversial theories on reconstructing pterosaurs led to some harsh critiques obscuring Peters’ artistic brilliance.” 

That’s okay.
“Very controversial” does not mean completely bonkers (or am I reading too little into this?). It just means it inspires a lot of chatter. Or… it could mean that the author of the post follows the invalidated observations of Elgin, Hone and Frey 2010, which are the traditional views (Unwin and Bakhurina 1994), still used in David Attenborough films. If so, that would be a shame. Science is usually black and white – is or isn’t, because you can observe and test (Fig. 5) and all tests, if done the same, should turn out the same.

And you don’t toss out data
that doesn’t agree with your preconception, like Elgin, Hone and Frey did. In reality, my “very controversial reconstructions” remain the only ones built with DGS, not freehand guesswork or crude cartoonish tracings (as in Elgin, Hone and Frey 2010). The membranes (brachiopatagia and uropatagia) were documented in precise detail in Peters 2002, 2009 and here online.

Click to animate. This is the Vienna specimen of Pterodactylus, which preserves twin uropatagia behind the knees.

Figure 5. Click to animate. This is the Vienna specimen of Pterodactylus, which preserves twin uropatagia behind the knees.

References
Elgin RA, Hone DWE and Frey E 2011. The extent of the pterosaur flight membrane. Acta Palaeontologica Polonica 56 (1), 2011: 99-111. doi: 10.4202/app.2009.0145
Peters D 2002. A New Model for the Evolution of the Pterosaur Wing – with a twist. – Historical Biology 15: 277–301.
Peters D 2009. A reinterpretation of pteroid articulation in pterosaurs. Journal of Vertebrate Paleontology 29:1327-1330.
Romer AS 1972. 
The Chañares (Argentina) Triassic reptile fauna. An early ornithosuchid pseudosuchian, Gracilisuchus stipanicicorum, gen. et sp. nov. Breviora 389:1-24.
Unwin DM and Bakhurina NN 1994. Sordes pilosus and the nature of the pterosaur flight apparatus. Nature 371: 62-64.

wiki/Gracilisuchus
paleoartistry.webs.com/1980s.htm

Guaibasaurus: a theropod! (Not a sauropodomorph)

Just look at it!!
With those very short, sharply-clawed forelimbs, how could anyone misidentify Guaibasaurus as ancestral to sauropods? And yet several big-name paleontologists did exactly that, most recently Baron et al. 2017.

Figure 1. Tiny forelimbs with three sharp-clawed fingers indicate that Guaibasaurus is a theropod, not a sauropodomorph. Shown to scale with related theropods Marasuchus and Procompsognathus.

Figure 1. Tiny forelimbs with three sharp-clawed fingers indicate that Guaibasaurus is a theropod, not a sauropodomorph. Shown to scale with related theropods Marasuchus and Procompsognathus. The posture of this skeleton is similar to the resting position of birds, which are also theropods.

Guaibasaurus candelariensis (Bonaparte et al., 1999, 2007; UFRGS PV0725T; Late Triassic) is known from an articulated skeleton lacking a neck and skull. Originally considered a basal theropod, later studies allied it with basal sauropodomorphs. Here this specimen nests as a basal theropod in a rarely studied clade. In the large reptile tree (LRT, 1018 taxa) Guaibasaurus nests between Segisaurus and Marasuchus + Procompsognathus (Fig. 1).

Wikipedia reports:
José Bonaparte and colleagues, in their 1999 description of the genus, found it to be possible basal theropod and placed it in its own family, Guaibasauridae. Bonaparte and colleagues (2007) found another early Brazilian dinosaur Saturnalia to be very similar to it, and placed the two in the Guaibasauridae which was found to be a primitive saurischian group. Bonaparte found that these forms may have been primitive sauropodomorphs, or an assemblage of forms close to the common ancestor of the sauropodomorphs and theropods. Overall, Bonaparte found that both Saturnalia and Guaibasaurus were more theropod-like than prosauropod-like. However, all more recent cladistic analyses found the members of Guaibasauridae to be very basal sauropodomorphs, except Guaibasaurus itself which was found to be a basal theropod or alternatively a basal sauropodomorph.”

On a similar note, Ezcura 2010 report, 
“A phylogenetic analysis found Chromogisaurus to lie at the base of Sauropodomorpha, as a member of Guaibasauridae, an early branch of basal sauropodomorphs composed of Guaibasaurus, Agnosphitys, Panphagia, Saturnalia and Chromogisaurus.” See Figure 2. We need to realize there are some phytodinosaurs, like Eoraptor, Eodromaeus, Panphagia and Pampadromaeus, that are outside of the Sauropodomorpha and outside the Ornithischia. The greater paleo community has not recognized this yet.

Figure 2. Taxa variously considered members of the Guaibasauridae. Here the top few nest with or closer to Sauropodomorpha. The bottom taxa nest with theropods in the LRT.

Figure 2. Taxa variously considered members of the Guaibasauridae. Here the top few nest with or closer to Sauropodomorpha. The bottom taxa nest with theropods in the LRT. Note the small size of Marasuchus, Agnophitys and Procompsognathus. Evidently phylogenetic miniaturization was taking place here, but in this case we know of no ancestors. Maybe someday we will..

I realize the authors
of the Guaibasaurus Wiki article can’t take a stand nor do they choose to test the hypotheses of PhDs, but I can and do here. Science is all about testing observations, comparisons and analyses. When Baron et al. nested Guaibasaurus with the sauropodomorphs, and Eoraptor + Eodromaeus with theropods, and avoided including a long list of taxa from the only other archosaur clade, Crocodylomorpha. and avoided including a long list of taxa from the outgroup to the Archosauria, the Poposaurs, then their results have to be considered suspect at least and bogus at worst. Headline grabbing is fun and lucrative for paleontologists, but not always good for paleontology. So many mistakes have been chronicled that it’s getting to the point that discoveries need to be put on simmer and only lauded when other studies validate them. On the same note, referees are not being tough enough on manuscripts.

References
Baron MG, Norman DB, Barrett PM 2017. A new hypothesis of dinosaur relationships and early dinosaur evolution. Nature  543:501–506.
Bonaparte JF;Ferigolo J and Ribeiro AM 1999. 
A new early Late Triassic saurischian dinosaur from Rio Grande do Sol state, Brazil. Proceedings of the Second Gondwanan Dinosaur Symposium, National Science Museum Monographs. 15: 89–109.
Bonaparte JF, Brea G, Schultz CL and Martinelli AG 2007. A new specimen of Guaibasaurus candelariensis (basal Saurischia) from the Late Triassic Caturrita Formation of southern Brazil. Historical Biology, 19(1): 73-82.

Baby Limusaurus had teeth!

This is pretty remarkable.
Wang et al. 2016 reported on a growth series for Limusaurus (Xu et al. 2009; Jurassic, Oxfordian; 1.7m in est. length; IVPP V 15923; Figs. 1-5,) “the only known reptile to lose its teeth and form a beak after birth.”  

You might remember
Limusaurus became famous earlier for its tiny forelimbs complete with a digit 0 medial to digit 1, that made theropod workers go bonkers because they assumed the digits present were 1-4, not 0-3.

Figure 2. Limusaurus also has four fingers and a scapula with a robust ventral area, like Majungasaurus, but those four fingers are not the same four fingers found in Majungasaurus.

Figure 1. Limusaurus also has four fingers and a scapula with a robust ventral area, like Majungasaurus, but those four fingers are not the same four fingers found in Majungasaurus.

Wang et al. report,
“The available data are important for understanding the evolution of the avian beak.” Except… Limusaurus is not close to the avian line of ancestry anyway you look at it. The LRT nests Limusaurus, with or without teeth, with Khaan, a toothless, beaked oviraptorid. Wang et al. nest Limusaurus with Elaphrosaurus (Fig. 3) even though Khaan is part of their taxon list. So something is not scored right. Not sure about the discrepancy, but some of that could be due to the misidentification of manual digits 0-3.

Figure 3. Khaan, an oviraptorid that nests with Limusaurus in the large reptile tree AND the repaired Cau, Brougham and Naish tree.

Figure 2. Khaan, an oviraptorid that nests with Limusaurus in the large reptile tree AND the repaired Cau, Brougham and Naish tree.

Wang et al. report,
“The ontogenetically variable features (e.g. teeth/no teeth, etc.) have little effect on its phylogenetic position.” The LRT agrees. Wang et al. report that no matter which ontogenetic stage is tested for Limusaurus, it always nests with or near the ceratosaur, Elaphrosaurus (Fig. 3).The LRT disagrees.  In other words, with or without teeth, the topology does not change. In the LRT  toothed juvenile Limusaurus also nested with Khaan. Toothed Juravenator and Sinosauropteryx nest as sisters to that clade. The large Compsognathus specimen CNJ79 (Fig. 6) was a basal taxon. All of these sisters are closer to Limusaurus in size and morphology than is Elaphrosauru (Fig. 3).

Figure 3. Elaphrosaurus is known from a partial skeleton lacking a skull.

Figure 3. Elaphrosaurus is known from a partial skeleton lacking a skull. Adult Limusaurus added to scale. Wang et al. consider these two to be sister taxa among basal theropods, which is not confirmed by the LRT.

The ontogenetic series of Limusaurus
is shown in figure 4. Not all the specimens are complete. None are shown to scale. All are portrayed as tiny rough tracings. I think this lack of detail is one shortcoming of the paper.

Figure 4. Specimens attributed to Limusaurus, not to scale.

Figure 4. Specimens attributed to Limusaurus, not to scale, from Wang et al. 2016.

Wang et al. also provided
reconstructions of a juvenile and adult Limusaurus (Fig. 5). Unfortunately, Wang et al. filled in all the missing bones and gave both reconstructions something of a generic theropod character, lacking some of the traits unique to this genus.

Limusaurus reconstructions from Wang et al. 2016, to scale and not to scale.

Figure 5. Limusaurus reconstructions from Wang et al. 2016, to scale and not to scale. The angle of the pubis is difficult to determine.

That Limusaurus juveniles had teeth
and adults did not, tells us less about the avian line and more about the oviraptorid line of theropod dinosaurs.

Figure 1. The large (from Peyer 2006) and small Compsognathus specimens to scale. Several different traits nest these next to one another, but at the bases of two sister clades. Note the differences in the forelimb and skull reconstructions here. There may be an external mandibular fenestra. Hard to tell with the medial view and shifting bones.

Figure 6. The large (from Peyer 2006) and small Compsognathus specimens to scale. Several different traits nest these next to one another, but at the bases of two sister clades. Note the differences in the forelimb and skull reconstructions here. There may be an external mandibular fenestra. Hard to tell with the medial view and shifting bones.

References
Wang S, Stiegler J, Amiot R, Xu W, Du G-H, Clark JM, Xu X 2016. Extreme ontogenetic changes in a ceratosaurian theropod. Currently Biology 27:1-5 plus SupData.

Full scale models from the vault

Back in the day
when I was writing and illustrating dinosaur books (1988~1992) I also built a few full scale models that I intended to use as subjects for paintings and museum displays. Here are most of them. Other models include the pterosaur skeletons you can see here.

Figure 1. Brachiosaurus skull, carved out of wood. Full scale.

Figure 1. Brachiosaurus skull, carved out of wood. Full scale.

At this point in my life
(1990s) the work (paintings / illustrations) was considered ‘acceptable.’ Even my papers were ‘acceptable.’ Unfortunately, when I started applying phylogenetic analysis to taxa and discovering new and overlooked relationships (published at ReptileEvolution.com, ) my work and manuscripts were no longer considered ‘acceptable,’ despite the fact that early discoveries made here are being re-discovered and validated years later by PhDs.

FIgure 2. Camarasaurus baby model. Full scale.

FIgure 2. Camarasaurus baby model. Full scale.

This Dimorphodon
(Fig. 3) was among the first of the models, based on Kevin Padian’s 1983 running illustrations.

Figure 3. Dimorphodon skull with dog hair for pycnofibers.

Figure 3. Dimorphodon skull with dog hair for pycnofibers.

Not sure why I produced this plesiosaur
because it took up a bunch of garage space and only entertained the mailman. Ultimately it was purchased by the AMNH, but never put on display. Where it is now is anyone’s guess.

Figure 4. Plesiosaur model. Full scale.

Figure 4. Plesiosaur model. Full scale. See figure 5 for the face.

Much of this plesiosaur
was fashioned at the late Bob Cassilly studios, who was a famous St. Louis sculptor and founder of The City Museum. Bob contacted me after seeing my book, Giants, because he had been commissioned to produce some of the giant marine animals pictured therein. Through that friendship in the 1990s, I was able to study specimens, including Sharovipteryx and Longisquama, from the traveling Russian Dinosaur Exposition that came to the City Museum for their first stop.

Figure 5. Plesiosaur model head detail. Full scale. Teeth are tree thorns.

Figure 5. Plesiosaur model head detail. Full scale. Teeth are tree thorns.

Among the smaller full scale models
is this sparrow-sized Pterodactylus in a bipedal pose (Fig. 6), ready to take flight.

FIgure 6. Pterodactylus scolopaciceps (n21) model. Full scale.

FIgure 6. Pterodactylus scolopaciceps (n21) model. Full scale. Later I learned that this genus was plantigrade (flat-footed), when quadrupedal. This one is about to take flight from a bipedal configuration. Digitigrady at this instance would have given Pterodactylus a bit more power in its initial leap during take-off.

And based on the evolution book

From the Beginning, these three (Fig. 7) are fleshed out steps in the evolution of tetrapods, cynodonts, mammals and man. Ichthyostega is a bit out of date now.

Figure 7. Ichthyostega, Osteolepis and Thrinaxodon, all more or less ancestral to humans. Full scale.

Figure 7. Ichthyostega, Osteolepis and Thrinaxodon, all more or less ancestral to humans. Full scale.

References
Padian K 1983. Osteology and functional morphology of Dimorphodon macronyx (Buckland) (Pterosauria: Rhamphorhynchoidea) based on new material in the Yale Peabody Museum, Postilla, 189: 1-44.

Feathered T-rex video: Excellent!*

The best video* I’ve seen on feathered dinosaurs.
*But note: their gliding Anchiornis forgot how to flap. Flapping came first. Then flapping with bipedal climbing. Then flapping with flying. Birds don’t come by gliding except to rest while airborne. Same with bats (if any glide ever). Same with pterosaurs. Let’s take gliding out of the equation for the origin of flight. That’s widespread antiquated thinking not supported by evidence. If you glide you do not flap. If you flap, some of your ancestors may learn to glide.

Click here or on the image to play.