ReptileEvolution.com update

It’s been awhile since I last updated ReptileEvolution.com.
Just sent off the third of three papers. So, I’ve been busy and it has been interesting discovering things along the way. The family trees for the Pterosauria and the Reptilia will not be updated until the publication of these works. Sorry about that.

Only a few poorly preserved taxa moved.
The tree topology remains the same. The navigation bars have been updated. Should make it easier to get around, especially if you know what you’re looking for.

While we’re on the subject,
It’s been two years since Darren Naish at Tetrapod Zoology took a swipe at ReptileEvolution.com. I don’t think he’ll notice or appreciate the changes, but I have been checking, double checking and getting new data. Not all of it is up yet (see above for the reason). As you know, I have been criticized, but I’m not married to any of this. I do put out what I’ve learned because Science, in all of its forms, needs to be tested. Are my tests correct? Maybe not. I’ve been wrong thousands of times. Getting it right in the end is my only goal here. At present things seem better than they were. More parsimonious. Sister taxa show gradual evolutionary changes, etc.

My posts have not been produced daily lately, like they were for the first 1000 or so. Whether I’m running out of steam, finding fewer things to talk about in this realm, or there has been a reduced flow of fun new paleo-discoveries, I don’t know.

For those who are interested…
Publication doesn’t guarantee acceptance or even discussion of novel discoveries. It’s been 14 years since Cosesaurus and kin were introduced as more parsimonious ancestors than any known archosaur/archosauromorph. Yet, pterosaur workers are still putting Euparkeria into their matrices when Parasuchus comes out closer on their tree. Very odd. Almost funny if it weren’t so tragic.

Along the same lines, if you google “Pterosaur pteroid” you’ll find a listing for an Ask the Biologist answer on this subject that is surprising given that the origins of the pterosaur pteroid were published in 2002 and 2009. Experts Mark Witton and Dave Unwin in their books on pterosaurs likewise ignore published literature and report that the origin of the pteroid remains an unsolved mystery.

While I’ve gotcha…
I would like to turn you all on to a pretty sharp dinosaur YouTube video I saw recently that I’m probably the last one on the block to hear about. Surprisingly the theropods all have what seems to be an appropriate amount of feathers. Even the big ones!

It’s about an hour and eleven minutes. Not too hokey, either. Enjoy!

https://www.youtube.com/watch?v=9VkfyB_bGYo

Figure 1. March of the Dinosaurs on YouTube. Click to Watch. 1:11:00

Figure 1. March of the Dinosaurs on YouTube. Click to Watch. 1:11:00

The most primitive Choristoderes?

Choristoderes
are a difficult clade to figure out both inside and out.

Wikipedia reports, “Champsosaur skulls are actually very similar to lizard skulls, though heavily modified. This has led some researchers to consider champsosaurids as lepidosauromorphs. However, champsosaurs lack the complex quadrate of lepidosaurians. With features of both diapsid groups, the phylogenetic position of Choristodera is highly confused.”

Matsumoto et al. (2007) reports, “This tree confirms the monophyly of Neochoristodera (Evans and Hecht1993) including Champsosaurus, Ikechosaurus, Simoedosaurus, and Tchoiria. The relationships of the non−neochoristoderan taxa have been more controversial. In our analysis, the Jurassic Cteniogenys retains a basal position, with the Chinese Philydrosaurus (Gao and Fox 2005) one node above it.”

Note the loss of resolution at the base of their tree (Fig. 1).

Figure 1. The family tree of the Choristodera according to Matsumoto et al. 2007. Early eras added in color. Note that ancestral taxa were large and long-snouted with four temporal openings, not two.

Figure 1. Click to enlarge. The family tree of the Choristodera according to Matsumoto et al. 2007. Early eras added in color. Note that some ancestral taxa, like Diandongosuchus, were large and long-snouted. Others were small, like the BPI specimen of Youngina, but equally long snouted. So the long-snouted forms may be more primitive. Note the loss of resolution at the clade base.

The question in the Matsumoto et al. 2007 tree is what happened in pre-Jurassic times? In 2007 Youngina was indeed the best outgroup taxon, but several varieties are known and some of these have a longer rostrum. Unfortunately these were overlooked as Matsumoto et al. focused on known choristoderes. In 2012 the large younginidDiandongosuchusbecame known. While it nests at the base of the parasuchia, it also nests at the bases of the Choristodera and Chanaresuchia. Yes, it has an antorbital fenestra, and so do some Youngina specimens. It is possible that the Choristodera secondarily lost their aof. Or they never had one.

In any case, the large reptile tree recovered a similar basal split between the large and small choristoderes, but with complete resolution among the five small ones and three large ones. More precision in the character scoring of the various Youngina specimens should add clues to this mystery. Don’t discount those subtle variations!

References
Matsumoto R, Evans SE and Manabe M 2007. The choristoderan Monjurosuchus form the Early Cretaceous of Japan. Acta Palaeontologica Polonica 52(2):329-350.

 

Another lateral temporal fenestra!

Figure 1. Emeroleter skull showing lateral temporal fenestra, as also shown in its sisters Macroleter, Romeriscus and Lanthanosuchus.

Figure 1. Emeroleter skull showing lateral temporal fenestra, as also shown in its sisters Macroleter, Romeriscus and Lanthanosuchus. Images from Tsuji, Müller and Reisz 2012.

This looks like a regular break (Fig. 1), but Emeroleter nests between taxa that also have a lateral temporal fenestra (Fig. 2). So this could be a real lateral temporal fenestra made ragged over the last tens of millions of years.

Figure 2. Macroleter, Emeroleter, Romeriscus and Lanthanosuchus in phylogenetic order and to scale. All have a lateral temporal fenestra.

Figure 2. Macroleter, Emeroleter, Romeriscus and Lanthanosuchus in phylogenetic order and to scale. All have a lateral temporal fenestral, even if small. This is a better evolutionary sequence leading to Lanthanosuchus than Acleistorhinus can provide.

At this stage in lepidosaurormorph evolution, taxa were just beginning to experiment with the lateral temporal fenestra, which was “here to stay” in owenettids, like Sauropareion.

However, the last time we see the lower temporal bar (jugal/ quadratojugal connection) is right here (Fig. 2) until these two bones are reconnected again in basal sphenodontians, drepanosaurs and fenestrasaurs.

DeBraga and Reisz (1996) and Cisneros (2004) reported that Acleistorhinus was the sister to Lanthanosuchus. However, the large reptile tree indicates a better match with Romeriscus, Emeroleter and Macroleter. Acleistorhinus makes a better sister to the turtle-like millerettid, Eunotosaurus.

Tsuji et al. 2012 reported, “A clade consisting of the nycteroleters and pareiasaurs, here termed Pareiasauromorpha, is supported by both methods.” Unfortunately, it is not supported by the large reptile tree, unless all subsequent taxa that have these taxa at their base are also called pareiasauromorphs, and that would include all turtles, lizards and snakes, and Lanthanosuchus, which Tsuji et al. 2102 also nested with Acleistorhinus far from Emeroleter. 

References
Cisneros et al 2004. A procolophonid reptile with temporal fenestration from the Middle Triassic of Brazil. Proceedings of the Royal Society London B (2004) 271, 1541–1546 
deBraga M and Reisz RR 1996. The Early Permian reptile Acleistorhinus pteroticus and its phylogenetic position. Journal of Vertebrate Paleontology 16(3): 384–395. doi:10.1080/02724634.1996.10011328.
Modesto SP, Damiana RJ and Sues H-D 2002. A reappraisal of Coletta seca, a basal procolophonid reptile from the lower Triassic of South Africa. Palaentology 45(5):883-895.
Tsuji, Müller and Reisz 2012. Anatomy of Emeroleter levis and the Phylogeny of the Nycteroleter Parareptiles. Journal of Vertebrate Paleontology 32 (1): 45-67. doi:10.1080/02724634.2012.626004.

wiki/Emeroleter

 

Scandensia is a key taxon at the base of the Squamata

Changes made December 04, 2014 to renest Scandensia basal to the Squamates, not the Lepidosauria.

From the Early Cretaceous of Spain, 
Scandensia has been described as “an unusual lizard” and “enigmatic.”

From Bolet and Evans 2011
“The original description of Scandensia (Evans and Barbadillo 1998) established that it was a squamate (e.g. jaw and tooth morphology, emarginated scapulocoracoid fenestrate clavicle, absence of gastralia) and this is confirmed by the new specimen (e.g. co-ossification of the pelvic bones, pubic morphology). The first phylogenetic analysis (Evans and Barbadillo 1998), using PAUP and a modified version of the Estes et al. (1988) matrix, put Scandensia in a basal position on the squamate stem.”

Figure 1. Scandensia a basal lepidosaur

Figure 1. Scandensia a basalmost squamate.

The present analysis confirms that nesting
Here Scandensia nests at the base of the Squamata, which means it was relic from the Early Permian living in the Early Cretaceous. Tendril-like fingers and toes mark it as arboreal.

The misnamed “Langobardisaurus” rossii, MFSN 19235, is the current larger outgroup taxon.

Figure 2. Langobardisaurus(?) rossii (MFSN 19235) reconstructed. Here it nests between basal sphenodontids and basal tritosaurs + squamates.

Figure 2. Langobardisaurus(?) rossii (MFSN 19235) reconstructed. Here it nests between basal sphenodontids and basal tritosaurs + squamates. Probably not a climber, but a digger.

There’s a whole other world of lepidosaurs being discovered that don’t fit into the established clades like the Sphenodontia and the Squamata. The Tritosauria are among them, but other clades, like the one that includes Scandensia and MFSN 19235, are out there and more should be expected.

References
Evans SE and Barbadillo LJ 1998. An unusual lizard (Reptilia: Squamata) from the Early Cretaceous of Las Hoyas, Spain. Zoological Journal of the Linnean Society 124:235-265.
Bolet A and Evans SE 2011. New material on the enigmatic Scandensia, an Early Cretaceous lizard from the Iberian Peninsula. Special Papers in Palaeontology 86:99-108.

A new face for Sclerosaurus – at the base of the Pareiasauria

Sclerosaurus armatus (Meyer 1859) Middle Triassic ~50 cm in length, was originally considered a procolophonid, then a pareiasaurid, then back and forth again and again, with a complete account in Sues and Reisz (2008) who considered it a procolophonid.

Earlier I reconstructed a lower face for Sclerosaurus, a taxon known from a fossil that has been flattened but still has 3D elements. Unfortunately the top of the snout is missing, but most of the rest of the skull is present in 3D or in impressions. A recent review (what I’ve been doing for the last few months) brought new insight and a higher, more box-like face.

Figure 3. Soft shell turtle evolution featuring Arganaceras, Sclerosaurus, Odontochelys and Trionyx.

Figure 3. Soft shell turtle evolution featuring Arganaceras, Sclerosaurus, Odontochelys and Trionyx.

Sclerosaurus is a sister to Elginia, the pareiasaur with really big horns! Sclerosaurus is also a sister to Arganaceras, the basal pareiasaur or pareiasaur cousin with vestigial horns.

Arganaceras

Figure 2. Arganaceras, as originally reconstructed and modified. This taxon nests as a sister to Sclerosaurus and together they nest as the sister to the Pareiasauria. See the reduced horn on the suptratemporal?

Classic pareiasaurs, like Anthodon (Fig. 3), don’t have supratemporal horns, but they do raise the tabular and postparietals to the dorsal plane from the ancestral occipital plane. This is a big reversal since anamniotes also have tabulars and post parietals on the dorsal plane and intervening taxa do not.

Anthodon

Figure 3. Anthodon in various views from Lee (1997).

The outgroup taxon for pareiasaurs is the Early Permian giant millerettidStephanospondylus. The skeleton is poorly known, but no horns were present.

Figure 8. Click to enlarge. Stephanospondylus based on parts found in Stappenbeck 1905. Figure 8. Click to enlarge. Stephanospondylus based on parts found in Stappenbeck 1905. Several elements are re-identified here. Note the large costal plates on the ribs, as in Odontochelys. The pubis apparently connected to a ventral plastron, not preserved. The interclavicle was likely incorporated into the plastron.

Figure 4. Click to enlarge. Stephanospondylus based on parts found in Stappenbeck 1905. Several elements are re-identified here. Note the large costal plates on the ribs, as in Odontochelys. The pubis apparently connected to a ventral plastron, not preserved. The interclavicle was likely incorporated into the plastron.

These wide-body omnivores/herbivores had to protect themselves from coeval predators. Turtles did this best. The rest went extinct for one reason or another. But these taxa give us the best picture of the many directions evolution took to solve the basic defense question.

References
Sues H-D and Reisz RR 2008. Anatomy and Phylogenetic Relationships of Sclerosaurus armatus (Amniota: Parareptilia) from the Buntsandstein (Triassic) of Europe. Journal of Vertebrate Paleontology 28(4):1031-1042. doi: 10.1671/0272-4634-28.4.1031 online

Sclerosaurus paleocritti

 

The Beauty and Benefit of Crushed Fossils

This photo an 16th century galleon in the Baltic reminded me that similar crushed fossils sometimes provide more data at a glance than first meets the eye.

Figure 1. A sunken flattened ship is like a sunken flattened pterosaur fossil. Here the lateral view is easy to see and the dorsal view can be reconstructed from the loose planks.

Figure 1. A sunken flattened ship is like a sunken flattened pterosaur fossil. Here the lateral view is easy to see and the dorsal view can be reconstructed from the loose planks.

Here is the R156 specimen of Dorygnathus about to eat a displaced femur.

Figure 2. The R 156 (Uppsala) specimen of Dorygnathus. Crushed and scattered like a sunken galleon.

Figure 2. The R 156 (Uppsala) specimen of Dorygnathus. Crushed and scattered like a sunken galleon.

And here is how the displaced ‘planks’ (in this case, phalanges) can get put back together using DGS (digital graphic segregation) techniques: colorizing the bones then moving the colors into a reconstruction, checking with PILs. A little intuition and experience also helps.

Figure 3. The disarticulate pes of Dorygnathus here reconstructed using DS into a complete pes.

Figure 3. The disarticulate pes of Dorygnathus here reconstructed using DS into a complete pes. Wondering now whether or not those metatarsals were splayed or appressed when walking. 

References
Padian K 2009. The Early Jurassic Pterosaur Dorygnathus banthenis (Theodori, 1830) and The Early Jurassic Pterosaur Campylognathoides Strand, 1928, Special Papers in Paleontology 80, Blackwell ISBN 9781405192248

Czerkas and Feduccia disconnect birds and dinos

Figure 1. Reconstruction of Scansoriopteryx with possible feather extent by Stephen Czerkas. Good thing that second branch or telephone wire is available for balance!

Figure 1. Reconstruction of Scansoriopteryx with possible feather extent by Stephen Czerkas. Good thing that second branch or telephone wire is available for balance!

A new paper by Czerkas and Feduccia
attempts to unlink birds with dinosaurs and to link birds with some unspecified archosaur by their reexamination of Scansoriopteryx, a tiny Chinese fossil of the Jurassic. Much has already been said about this paper — all negative.

Czerkas and Feduccia report the “absence of fundamental dinosaurian characteristics,” but do not do so with phylogenetic analysis, which would have nested their study subject somewhere else that they could support, but can’t. They seem stuck in a trees-down vs. ground up battle when plenty of ground-dwelling dinosaurs seem fully capable of climbing a tree by grappling or simply by running up a vertical trunk bipedally, as some modern birds do (any Dial reference below). Their illustration (Fig. 1) seems to say that whether bird or dinosaur or non-dinosaur, Scansoriopteryx was not capable of standing balanced on its (apparently splayed?) hind limbs, despite the fact that it’s forelimbs appear poorly designed for walking. They’ve been accused of LarryMartinizing and it seems they have indeed been doing so. For those interested, Larry Martin preferred to discuss individual characters rather than suites of characters of a sort used in phylogenetic analysis.

I can’t buy into their particular heresy.
There’s no support for it. We need to see details and analyses. And they need to present their best alternative candidate among the non-dinosaurian archosaurs out there as a sister to Scansoriopteryx. 

The irony here
is that the same sort and style of argumentation is being used to support a pterosaur/archosaur connection by the same set of paleontologists who support the dino/bird connection. By that I mean, they present no archosaurian candidates that more closely match pterosaurs than our own favorites: the lepidosaur, tritosaur, fenestrasaurs.

So, if you’re a finger pointing paleontologist, be careful. Don’t fall into  that same trap.

References
Czerkas SA and Feduccia A 2014. Jurassic archosaur is a non-dinosaurian bird, Journal of OrnithologyDOI: 10.1007/s10336-014-1098-9
Dial KP, Jackson BE and Segre P 2008.  A fundamental avian wing-stroke provides a new perspective on the evolution of flight. Nature (online 23 Jan 08)
Padian K and Dial KP 2005. Could the “Four Winged” Dinosaurs Fly?  Nature: 438:E3-5.
Dial KP, Randall R and Dial TR 2006. What use is half a wing in the evolution of flapping flight? BioScience 56: 437-445.
Tobalske BW and Dial KP 2007. Aerodynamics of wing-assisted incline running. J. Exp. Biol. 210:1742-1751.
Bundle MW and Dial KP  2003. Mechanics of wing-assisted incline running.  J. Exp. Biol., 206:4553-4564.
Dial KP 2003.  Evolution of avian locomotion: Correlates of body size, reproductive biology, flight style, development and the origin of flapping flight. Auk 120:941-952.
Dial KP 2003. Wing-assisted incline running and the evolution of flight.  Science 299:402-404.
Read more at: http://phys.org/news/2014-07-declassify-dinosaurs-great-great-grandparents-birds.html#jCp