When cladograms go bad…

Figure 1. Diandongosaurus exposed in ventral view, skull in dorsal view. Note the small size. At 72 dpi this image is 6/10 the original size.The last common ancestor of Diandongosaurus and Pachypleurosaurus was a sister to Anarosaurus at the base of the Sauropterygia.

A recent paper (Liu et al. 2015) on a new specimen (BGPDB-R0001) of the basalmost placodont, Diandongosaurus, (IVPP V 17761), brings up the twin problems of taxon inclusion/exclusion without the benefit of a large gamut cladogram, like the large reptile tree (580 taxa) to more confidently determine inclusion sets in smaller more focused studies (anything under 100 taxa).

Let’s start by making the large reptile tree go bad.  
Liu et al. used a traditional inclusion set (Fig. 1 on left) that included suprageneric taxa and taxa that were unrelated to one another in the large reptile tree (Fig. 1 on right). To illustrate inherent problems, I reduced the taxon list of the large reptile tree to closely match that of Liu et al. See them both here (Fig.1).

Figure 1. Click to enlarge. Left: Liu et al. cladogram. Diandongosaurus is in dark purple. Right: matching taxa from the large reptile tree. Note, this taxon mix is not a valid subset of the large reptile tree. “?” indicates probable transposition of taxa in the Liu et al tree as Rhynchosaurs typically nest with Trilophosaurus and Rhynchodephali typically nest with Squamates in traditional trees. They nest together in the large reptile tree. note the nesting of turtles (at last : ) with archosauriformes! This shows graphically how twisted cladograms can get with taxon exclusion issues.

Although many taxa on the left and right of figure one are similar, many nest differently.

Let’s start with the problems
in the cladogram on the right, in the reptileevolution.com incomplete cladogram

1. Prolacerta nests basal to squamates (Iguana) and Triassic gliders (Kuehneosaurus).
2. Trilophosaurus nests between squamates and rhynchocephalians.
3. Turtles nest with archosauriforms and both close to rhynchosaurs, none of which are related to each other in the large reptile tree. This is the wet dream of many turtle workers intent on matching DNA studies that place turtles with archosaurs, a clear case of DNA not matching morphology.

Everything else
is basically in the correct topology, remarkable given that 540 or so taxa are missing.

The problems in the cladogram on the left,
from Liu et al include:

• Turtles nest between Triassic gliders and placodonts (and not the shelled ones proximally). This is Rieppel’s insistence on a force fit. Is the insertion of turtles the reason for other tree topology disturbances here and on the right? Not sure…
• Hanosaurus, a derived pachypleurosaur close to nothosaurs nests with Wumengosaurus, a pachypleurosaur/stem ichthyosaur.
• Liu et al. nested Diandongosaurus with headless Majiashanosaurus (which is correct) but then nests both at the base of the nothosaurs (which is not validated by the large reptile tree). The large reptile tree nested Diandongosaurus at the base of the placodonts, between Anarorosaurus and Palatodonta + Majiashanosaurus. Shifting Diandongosaurus to the base of the nothosaurs adds 32 steps to the large reptile tree.

Perhaps what the Liu et al team need is a subset of the large reptile tree. That would help them drop those turtles from placodont studies. They don’t belong. When cladograms go bad, sometimes there are included taxa that should not be there. Colleagues, make sure to check your recovered sister taxa to make sure they look like they could be sister taxa. After all, evolution is about slow changes over time.

References
Liu X-Q, Lin W-B, Rieppel O, Sun Z-Y, Li Z-G, Lu H and Jiang D-Y 2015. A new specimen of Diandongosaurus acutidentatus (Sauropterygia) from the Middle Triassic of Yunnan, China. Vertebrata PalAsiatica. Online Publication.

 

The other Slavoia and the holotype

Earlier we looked at the basal amphisbaenid, Slavoia darevskii (Fig. 3 below, Talanda 2015).

I just read about the holotype (Sulminski 1984) and at least 45 other specimens attributed to Slavoia, like this one (Fig. 1, ZPAL MgR-III/77, Campanian, Late Cretaceous). Six of the 46 skulls are associated with postcranial skeletons, like the holotype, Fig. 2, ZPAL MgR-I/8). If you think this skull looks like Macrocephalosaurus, you’re not the only one.

Slavoia specimen ZPAL MgR III/77, one of 46 skulls,  nests not with amphisbaenids, but with Macrocephalosaurus, a contemporary from the same horizon. Talanda reports, “The specimen has only half of the elements visible in this drawing. The skull roof and the middle part are not preserved.”

Sulminski nested Slavoia with scincomorphan lizards, but he reported, “It is interesting that described here lizard displays some characters similar to macrocephalosaurid and polyglyphanodontid  species discovered in the same localities of Mongolia. This concerns also particularly the structure of the temporal region, palatal construction and in number of teeth.”

The #77 and #8 specimens nested with macrocephalosaurs in the large reptile tree.

On the other hand,
the #112 specimen nested at the base of the amphisbaenids, as we learned earlier. So the #112 specimen needs a new generic name, or there are other issues that need be dealt with.

Dragging
the amphisbaenid #112 specimen over to the macrocephalosaur specimens adds 17 steps to the most parsimonious tree score. That’s a very low number considering that there are only 17 taxa separating the macrocephalosaurs from the amphisbaenids in the large reptile tree. So, there is a bit of convergence going on here between the macrocephalosaurids and amphisbaenids. The authors note all the skulls vary in size and shape, which they attribute to ontogeny and intraspecific variation. And, of course, none are perfectly preserved. Talanda reports, “The [#77] specimen has only a half of the elements visible in this drawing. The skull roof and the middle part are not preserved.”

Figure 2. The holotype of Slavoia (#8) compared to the lateral view skull (#77). While larger, the #77 skull is relatively shorter. These two nest together in the large reptile tree along with macrocephalosaurids. Note the large size of the limbs.

Does this represent a solution?
Sulimski (1984) recognized the similarity between his skinks and macrocephalosaurids. Talanda (2015) considered his specimen a basal amphisbaenid, a clade derived from skinks in the large reptile tree, but Talanda nested his amphisbaenids between Cryptolacerta and Dibamus + snakes. So there is disagreement here.

Figure 3. The #112 specimen from Talanda 2015 which both he and I nested as a basal amphisbaenid. Note the similarity to macrocephalosaurids (above). The teeth appear to be more robust here, as they are in the palate view specimens that have more of an amphisbaenid palate. I don’t see large limbs here, but limb size varies in the amphisbaenids.

Phylogeny is sometimes simple and straightforward.
Sometimes it is not.

This case shows the importance
of using specimen-based taxa in analyses, not specific, generic or suprageneric taxa. It would not be okay to take the best traits from several Slavoia specimens because some may not be Slavoia specimens! This case also highlights a need to determine where every one of these varied Slavoia specimens do nest. And it will be okay if some are lumped while others are split.

The limbs are large in the #8 specimen, but are not visible in the #112 specimen. In amphisbaenids limbs, even in basal taxa, can be vestiges, but not vestiges in the very derived Bipes.

We all have a lot to learn here. It’s not all set in stone.

References
Sulimski A 1984. A new Cretaceous scincomorph lizard from Mongolia. Palaeontologia Polonica, 46, 143–155.
Talanda M 2015. Cretaceous roots of the amphisbaenian lizards. Zoologica Scripta. doi:10.1111/zsc.12138

Romeriscus revisited…

Yesterday
I was working on a homepage graphic (look for it toward the bottom) listing dozens of basal reptile taxa on a timeline. I discovered that Romeriscus (Figs. 1, 2) was improperly nested chronologically and therefore, at least in this case, phylogenetically.

Romeriscus is represented by a crushed fossil
that has proven notoriously difficult to interpret (Fig. 1) and nest by all prior workers (see below). I reinterpreted the elements yesterday and now it seems to make more sense, both time-wise and morphologically. It now appears to be a basal archosauromorph reptile, a sister to Gephyrostegus watsoni (Fig. 2; which is not a sister to the holotype of the genus, G. bohemicus, and so G. watsoni needs a new name.)

Figure 1. Romeriscus GIF movie. Here is the in situ fossil from Laurin and Reisz 1992 along with several layers of colorized bone. See figure 2 for the reconstruction with matching bone colors. Click to enlarge. While missing the tail and lumbar region of the dorsals, the pelvis and elements from the two hind limbs were taphonomically shifted forward. Many of the bones are very poorly preserved, but most of the elements appear to be barely disarticulated.

Previously
I nested Romeriscus between Emeroleter and Lanthanosuchus, reconstructing it with a rather flat, wide skull. Today, I reconstruct the skull a bit less wide, but still >2x wider than tall. Back in the Westphalian, there was not so much diversity in reptiles, so what Romeriscus would look like, using DGS or not, was rather limited and therefor greatly simplified.  Skull width can often be determined from occipital and/or palatal elements, both of which are difficult to find on this fossil. Here (Fig. 2) skull width was determined by measuring the distance between the bases of the two still parallel quadrates, assuming that they did not move much during taphonomy.

Here Romeriscus
is reconstructed like and nests with another basal archosauromorph reptile, G. watsoni. Distinct from some, but not all basal gephyrostegids the limbs of Romeriscus are subequal in length. More below.

Figure 2. Romeriscus reconstructed using DGS, copying and pasting colorized bones into their in vivo places. The red quadrates are here, but are located almost invisibly behind the squamosal. I did not see an ischium, which is missing from this graphic.

Romeriscus perialllus (Baird and Carroll 1967, Early Pennsylvanian (Westphalian A, 306 mya, YPM-PU16 482) was originally considered a limnoscelid reptile and the earliest and most primitive reptile known in 1967. Laurin and Reisz (1992) considered it a tetrapod of unknown affinity and they considered limnoscelids as anamniotes. They were unable to distinguish the various skull elements, but reinerpreted several of the interpretations of Baird and Carroll.

Using DGS I was able to identify most of the bones on the plate (Fig. 1). In the large reptile tree the resulting reconstruction (Fig. 2) nests with Gephyrostegus watsoni (Fig. 3).

Figure 3. Reconstruction of G. watsoni as a distinctly different genus, nesting with Romeriscus. It is separated from G. bohemicus by the genus Eldeceon.

Distinct from G. watsoni, 
Romeriscus was twice as large overall and with a more erect occiput. The orbit was 2x longer than tall. The naris was larger. The fore and hind limbs were similar in size. The frontals were wider and the parietals were narrower. The hind limb was narrower than the forelimb.

To those who think ReptileEvolution.com should still be ignored, the challenge is still out there… which taxa on the tree are improperly nested. I just found one, but I guess I’m finding ‘the low hanging fruit.’ the easy mistakes to pick out. Not sure if there are any more errors hidden in the tree. Only time and a critical eye will tell. Not happy finding any errors here, but I am happy correcting them.

Science is not okay with errors.
Science is better with corrections, but first the errors have to be uncovered. Look for things that just doesn’t fit established patterns. It could be that the established pattern is incorrect.

Baird and Carroll were correct in 1967.
Romeriscus was one of the most primitive reptiles known in that era. However, I don’t think they would have considered it a reptile if they knew Romeriscus retained an intertemporal bone, like many of its sisters. The loss of the intertemporal was considered an amniote trait, but the advent of the amniote egg preceded that loss according to the large reptile tree.

You can’t tell
what is a reptile and what is not by a list of traditional skeletal traits that somebody decided without a phylogenetic analysis. That sort of problem has hung up paleontologists for decades. You can only tell which taxa are the most basal reptiles by recovering the last common ancestor of dinosaurs and lizards in phylogenetic analysis. Presently that taxon is a sister to Gephyrostegus bohemicus, a late survivor (310 mya) of a much earlier (345 mya) reptile evolution and radiation from seymouriamorph sisters like Silvanerpeton (335 mya).

Speaking of errors,
if you see any here, with regard to Romeriscus or any other taxa, let me know ASAP, so I can clear those up.

References
Baird D and Carroll RL 1967. Romeriscus, the oldest known reptile. Science. 1967 Jul 7;157(3784):56-9.
Laurin M and Reisz RR 1992. A reassessment of the Pennsylvanian tetrapod Romeriscus. Journal of Vertebrate Paleontology 12(4): 524-527.

New basal amphisbaenid: Slavoia

An update here, September 28, 2015, looks at the holotype of Slavoia, which does not nest with the specimen described below. 

The amphisbaenids
are typically small burrowing skinks (according to the large reptile tree) with roots deeply preceding the very derived Tamaulipasaurus (Clark and Hernandez 1994, Figs. 1, 4) in the Early Jurassic. Because Tamaulipasaurus reacquired a quadratojugal it was considered a diapsid incerta sedis and is not included in any amphiisbaenid phylogenetic studies. This is a mistake rectified here.

Figure 1. Amphisbaenids recovered by the large reptile tree. Click to enlarge.

With the erroneous deletion
of Tamaulipasaurus, the fossil record of amphisbaneids does not go deeper than the Cretaceous. Many taxa are extant. That is why Talanda (2015) titled his recent paper, “Cretaceous roots of the amphisbaenian lizards.”

Talanda reports on
Slavoia darevskii (ZPAL McR-I.112, from the Late Cretaceous of Mongolia, Fig. 2). Slavoia does indeed nest as a basal amphisbaenid, but it is clear that it must be a late-surviving taxon of an earlier radiation with roots that must go back to the Triassic or Late Permian based on the presence of Tamaulipasaurus and other lepidosaurs.

Unfortunately
Talanda used the squamate cladogram of Gauthier et al. (2012) which nested amphisbaenids between a clade that included the burrowing helodermatid, Cryptolacerta, and the basal scleroglossan, Tupinambis, and a clade that included the amphisbaenid, Dibamus (Fig. 1) and snakes with highly derived burrowing snakes, like Leptotyphlops, nesting with the very basal snake Dinilysia.

Missing from the Gauthier et al./Talanda cladogram
are the large reptile tree sisters to Slavoia, the extant Sirenoscincus and the extinct and odd, Sineoamphisbaena.

Furthermore
in the Gauthier et al./Talanda cladogram the basal gekko, Tchingisaurus nests as a sister to the aquatic pre-snake, Pontosaurus, which nests as a sister to the basal mosasaur, Aigialosaurus. Unfortunately, these taxa are all separated by several other taxa, often in widely separate clades, in the large reptile tree.

There is also an odd mix In the Gauthier et al./Talanda cladogram of proto-squamates mixed in with squamates. For instance, Carusi wrongly nests with the scerloglossan, Shinisaurus. Unfortunately Gauthier et al.and Talanda tree do not yet recognize or distinguish tritosaurs or protosquamates. Nor is there a recognition of the relationship between skinks and amphisbaenids or of geckos and snakes, all as recovered in the large reptile tree.

DGS
found a bone pattern distinct from that interpreted by Talanda who did not identify several bones found using the colorizing technique (Fig. 1).

Figure 2. Click to enlarge. Basal amphisbaenid Slavoia from Talanda 2015, showing in situ fossil, tracing by Talanda and colorizing added here. Several bones, like the lacrimal and prefrontal, are missing in the Talanda tracing, which evidently was not traced from this photograph. Every attempt was made to line it up, but only certain elements actually do line up with the Talanda tracing. Can you see the new quadratojgual there?

Given all these problems,
Slavoia is correctly nested as a basal amphisbaenid in the Talanda study. Slavoia provides good clues to the the evolution and morphology of its strange sister, Sineoamphisbaenia (Fig. 3), which it greatly resembles.

Figure 3. Sineoamphisbaena is a sister to Slavoia in the large reptile tree and shares a short rostrum and upper temporal bar with this taxon. The quadrate is prone in this taxon.

Getting back to Tamaulipasaurus…
Traditional paleontologists are loathe to consider Tamaulipasaurus an amphisbaenid, a scincoid, a scleroglossan or even a squamate because it has a complete lower temporal bar created in the usual way with a quadratojugal between a jugal and quadrate. However in this taxon the jugal lacks a postorbital process. A quadratojugal is typically not seen in amphisbaenids, scincoids, scleroglossans and squamates. Clark and Hernandez (1994) write: “The skull is superficially similar to that of burrowing squamates, especially amphisbaenians and dibamids, but the presence of plesiomorphic characters, such as a complete lower temporal bar, contradict a phylogenetic relationship within Squamata.”

The simple solution, of course, 
is to toss Tamaulipasaurus (Figs. 1, 4) into a large gamut cladogram to see where it nests most parsimoniously. And, to no surprise, it nests with derived amphisbaenids. No other of the the 580 tested taxa are closer (more similar). Despite the autapomorphy of the long lost reappearance of the quadratojugal in this one isolated taxon (and also perhaps in Slavoia (Fig. 2), all the rest of the traits of Tamaulipasaurus are amphisbaenid, very similar to Bipes (Fig. 1).

Figure 4. Tamaulipasaurus, distinct from nearly all squamates, has a quadratojugal and the jugal lacks a postorbital process. It is still an amphisbaenid.

Upon seeing the quadratojugal in Tamaulipasaurus,
Clark and Hernandez froze in their tracks and didn’t want to venture a solution more specific than “Diapsida”. That QJ bone wasn’t supposed to be there. And yet it was. Clark and Herenandez followed their textbooks instead of testing for parsimony in a large gamut cladogram.

It’s no big deal
We looked at the reappearance of the quadratojugal in other taxa here. So it happens every so often, and it happened again with Tamaulipasaurus.

Along the same lines,
we looked at the reappearance of digit zero in Limusaurus, the bird-like theropod, here. Extra phalanges and extra digits appear in certain plesiosaurs and ichthyosaurs. An extra skull bone appears anterior to the pineal foramen in dicynodonts. Extra vertebrae appear in a amphisbaenids and snakes. So an unexpected quadratojugal is nothing to freak out about.

References
Clark JM and Hernandez RR 1994. A new burrowing diapsid from the Jurassic La Boca formation of Tamaulipas, Mexico, Journal of Vertebrate Paleontoogy 14: 180-195.
Talanda M 2015. Cretaceous roots of the amphisbaenian lizards. Zoologica Scripta. doi:10.1111/zsc.12138

(Relatively) Giant Tanytrachelos Specimens!

We’re just talking about bits and pieces here,
but the new, giant New Mexico Tanytrachelos specimens (Pritchard et al. 2015) are a close match to the much smaller New Jersey specimens (Fig. 1). When you restore all the bones in between using the tiny specimens as blueprints, there are no obvious proportional differences between the two versions of Tanytrachelos (but size IS a factor in speciation — but that is another paleo-heresy).

Figure 1. Giant Tanytrachelos from New Mexico from Pritchard et al  2015, along with the much smaller specimens from New Jersey. Easier to imagine when all the parts are together and scaled to a blueprint. At top is the small specimen of Tanystropheus, all to scale.

Good description
by Pritchard et al (2015). And a good local nesting with Langobardisaurus and Tanystropheus and kin. Unfortunately, once you leave this vicinity in the Pritchard et al. cladogram (Fig. 2) sister taxa become wildly dissimilar (Mesosuchus, Teraterpeton and Macrocnemus together??). And the cladogram is missing several pertinent taxa (Fig. 3).

Figure 2. Pritchard et al. tree for Tanytrachelos. There are unrelated taxa here and related taxa are not included. See figure 3. Here two protorosaurs are widely separated. Other several purported sisters are indeed sisters in the large reptile tree, but others do not resemble one another and so could not have evolved from a common ancestor.

There is a much more gradual accumulation
of derived traits in the various sister cladded at the large reptile and large pterosaur trees, a subset of which is shown here (Fig. 3), where the lhyper-long-necked taxa are derived from long-necked taxa.

Figure 3. Tanytrachelos tree subset of the large reptile tree. Only a large gamut study can determine the inclusion set for more focused studies. You cannot rely upon tradition.

You can tell by the feet that tanystropheids are related to
fenestrasaurs and pterosaurs (Fig. 1). The very short metatarsal 5 along with a very long p5.1 is a shared trait of this clade that was named Characiopoda (“prop-footed ones” in Peters 2000). The clade includes Tanystropheidae + Langobardisaurus + Fenestrasauria.

Fenestrasauria = Cosesaurus, Sharovipteryx, Longisquama and Pterosauria (Peters 2000). This nomenclature and topology has been ignored by all workers for the last 15 years as they preferred to lump unrelated and dissimilar taxa together, preferring to pretend the origin of pterosaurs is a mystery, preferring NOT to look into this problem. When will reason return?

Also,
take a look at the skull of Tanystropheus (Fig. 1). All it is missing is an antorbital fenestra to become a pretty good pterosaur skull. You get such similarities through homology via relatedness.

As paleo-historians know,
the first specimens of Tanystropheus were considered pterosaurian largely due to their distinctive feet.

Good job!
to Pritchard et al. (2015) on their description and assessment for the giant Tanytrachelos.

It’s too bad
they were saddled with such a bad topology. I’m sure they realize that, like other lepidosaurs, Tanytrachelos has an ossified sternum and it is quite large, similar in shape to that of Huehuecuetzpalli, Langobardisaurus and Cosesaurus, three other tritosaur lepidosaurs. A large gamut study, like the large reptile tree, irons out all these problems.

Please, colleagues,
stop going with your gut, stop going with tradition and use the several times validated large reptile tree to help you determine inclusion sets for your more focused studies. Bigger (more taxa) is better. Or repeat the experiment yourself with a different set of characters and a large number of basal taxa. There is only one true tree of reptile evolution. Let’s find it together. Here is a good start with 580 taxa, fully resolved and with good bootstrap scores.

If anyone has Alan Turner’s ear
he disputed the ability of the large reptile tree to resolve 360 taxa with only 228 characters. There are now 220 more taxa here and no more characters, still fully resolved and going strong. Alan is not the only paleontologist who feels (and I used this word purposefully) this way. Most are anonymous referees. Alan was an editor on more than one of my manuscripts and contributed to the New Mexico Tanytrachelos paper (see refs).

References
Pritchard AC, Turner AH, Nesbitt SJ, Irims RB & Smith ND 2015. Late Triassic tanystropheids (Reptilia, Archosauromorpha) from northern New Mexico (Petrified Forest Member, Chinle Formation) and the biogeography, functional morphology, and evolution of Tanystropheidae. Journal of Vertebrate Paleontology 35(2):e911186, 20pp.

Some things you learn are not found in any textbooks…yet.

No current discoveries are found in the latest textbooks. 
That’s because it takes time (years typically) for textbooks to be (in reverse order) assigned, accepted, distributed, printed, edited, written and illustrated, researched and concepted. Textbook publishers are out to sell the maximum number of books, so they write to the current consensus, which may be in flux on several points and hypotheses. The current consensus may also be wrong–but it remains the consensus.

There are no courses
at any colleges entitled, PTEROSAURS 101, 102 or 103. Who would attend? There are only two dozen people in the world who have an interest, who study them, or contribute to what we know about them. And where is the consensus? On some points, there is no consensus!! And all too often “the consensus” is holding on to outmoded, invalid and unverifiable paradigms (see below).

Every new fossil specimen is really a new chapter
in an ever expanding textbook on paleontology. And all paleontologists who publish are contributing authors to that future textbook.

Striiving for veracity
It is important for all workers to see things as they are in specimens, and not to reinterpret them to fit an established paradigm, no matter the temptation to do otherwise. For instance, narrow chord wing preservation in pterosaurs is not the result of ‘shrinkage’ as some workers report. Rather it is what it is, universal. All pterosaur specimens have narrow chord wings. If you know one that is different, please tell me. I know one that appears different, but that’s because part of its arm was ripped away and displaced. Look closely. That’s the way it is.

If Galileo
went to school as a teenager and found the following question on a test: “If object A at ten pounds and object B at 10 ounces both fall from 1000 feet at the precisely the same moment, how many seconds ahead of B will A strike the ground?” He’d would not have even had the opportunity to choose answer E. “zero seconds.” Common knowledge at the time, based on Aristotle, would not have allowed it, no matter the facts of this case, proven by experiment. This went on for centuries.

Similarly,
if you were in college today and were given the multiple choice question, “Which one of the following taxa is most closely related to pterosaurs? A. Dinosaurs. B. Scleromochlus. C. Proterochampsids (including Lagerpeton). D. Euparkeria. E. Erythrosucids. F. We don’t know.” You would have to pick “F” to get a good score, because that’s the current consensus… unless your professor had recently written a paper espousing one of the other answers (see below). “G. None of the above” is the better answer according to the large reptile tree where fenestrasaurs are more closely related to pterosaurs. But each one of the above (A-E) has been proposed by recent authors, not caring if they made sense or not.

Imagine the plight of the poor student in Paleontology 101 today
when he or she asks the professor about that website, “repitleevoluton.com” The professor is going to have to say, “If you want a good grade, you’ll ignore that website and provide the same answers that are in your textbook.” That’s what Dr. Darren Naish  reported online. Don’t consider, test or discuss other possibilities. Best to ignore them — if you want to advance in paleontology and get your Masters or PhD.

Take, as an example,
David Hone’s dissertation that was later published in two papers in which he proposed comparing two competing pterosaur origin hypotheses, one by Peters 2000 (Cosesaurus, Sharovipteryx, Longiasquama) and one by Bennett 1996 (Scleromochlus) using the supertree method of analysis (combining several published analyses without actually examining any fossil specimens). Aware that his professor, Michael Benton, had earlier written a paper (Benton 1999) celebrating Scleromochlus as the sister to pterosaurs, Hone decided to delete and diminish the taxa proposed by Peters. He somehow created several typos in the Peters data and then deleted the entire Peters dataset because of those typos (references and the full story here). Then Hone and Benton (2008) gave credit for both competing hypotheses to Bennett while deleting all reference to Peters 2000. As a result, Hone received his PhD, two associated papers (Hone and Benton 2007, 2008) were published and Hone gained the ability to referee pterosaur manuscripts (like mine) submitted to academic journals. I wrote to Dr. Benton about the inconsistencies and leaps of logic between the two parts of their two part paper. His reply was a sheepish, “whoops. :  )”

See how it works? 
That’s how you crush an opposing hypothesis. And that’s just the tip of the iceberg of current readily solvable problems, as Pterosaur Heresies readers are well aware. No PhD wants to admit he/she was wrong. On some problems consensus will likely never be achieved — because in order to do so all invalid candidate hypothesis writers would have to admit they were wrong.

And that’s just not going to happen.
Not without a fight or a dismissal. Let me know if you know of any instances of someone admitting they were wrong (I know of one semi-wrong situation regarding Dr. Padian and his fight with pterosaur tracks). In the origin of snakes, pterosaurs, turtles and dinosaurs there are lots of ‘right’ answers out there, but few challenges to the weaker hypothesis and no one admits to being wrong.

As history tells us, in paleontology it takes decades to turn the boat around. And paleontologists don’t want anyone else, even other paleontologists, solving their mysteries for them… even when solutions are published in the literature.

Thanks for your interest.
I will continue to study and make informed comment on new fossil specimens, (many that haven’t made the textbooks yet). I will throw a spotlight on problems and celebrate solutions as they are verified or not in the large reptile tree. And I encourage you to do the same. If I can do it, anyone can do it.

There are too many paleontologists who
follow matrices, textbooks and papers blindly
and not enough paleontologists who have the balls to say, “Hey, there’s something wrong here.”

We’ll help fix the world of paleontology someday.
Unfortunately, it’s not going to happen this year. After four years of working with the large reptile tree, and improving it, and enlarging it year after year, it still has not been accepted for publication or gained intrigue among basal reptile workers. They don’t like it. It rocks the boat.

References
Bennett SC 1996. The phylogenetic position of the Pterosauria within the Archosauromorpha. Zoolological Journal of the Linnean Society 118: 261–308.
Benton MJ 1999. Scleromochlus taylori and the origin of the pterosaurs. Philosophical Transactions of the Royal Society London, Series B 354 1423-1446. Online pdf
Hone DWE and Benton MJ 2007. An evaluation of the phylogenetic relationships of the pterosaurs to the archosauromorph reptiles. Journal of Systematic Palaeontology 5:465–469.
Hone DWE and Benton MJ 2008. Contrasting supertree and total evidence methods: the origin of the pterosaurs. Zitteliana B28:35–60.
Peters D 2000. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.

The holotype of Nesodactylus is missing!

The holotype of Nesodactylus (Fig. 1) has been lost from the collection of the American Museum of Natural History. And it has been lost for several years. According to Carl Mehling of the AMNH, when asked about it this morning, “Sadly, it is still missing. But it did not disappear in the mail – No one seems to know what happened to it.”

Figure 1. Nesodactylus reconstructed. This taxon nests within various specimens of Campylognathoides in the large pterosaur tree.

Nesodactylus hesperius (Colbert 1969 ) AMNH FR 2000 Oxfordian, Late Jurassic ~158 mya, was considered a novel genus, but here it is derived from a sister to the C5 specimen of Campylognathoides and phylogenetically preceded the C3 specimen of Campylognathoides. That indicates Nesodactylus was a mislabeled specimen of Campylognathoides. It was much less complete than the other specimens.

So, who has Nesodactylus?
Raise your hand and send that specimen back to the AMNH!

References
Colbert EH 1969. A Jurassic Pterosaur from Cuba. American Museum Novitates, New York, 2370: 1-26.

wiki/Nesodactylus

News on the giant tube-snout sea turtle – Ocepechelon

Updated November 22, 2017
with a comparative image of Trionyx and Ocepechelon.

The weird ones really are more interesting, aren’t they?
For awhile I’ve wanted to study this weird putative chelonid turtle to see where it nests in the large reptile tree (now at 580 taxa). It’s not a chelonid, as originally interpreted by Bardet et al. (2013). Ocepechelon bouyai OCP DEK/GE 516 (Fig. 1), the famous suction-feeding giant sea turtle, nests with the soft-shell turtles, Odontochelys (Late Triassic) and Trionyx (post-Cretaceous). They share a longer rostrum, and several other traits, that short-beaked chelonids just don’t have.

Figure 1. Ocepechelon in lateral, anterior and occipital views. There is no premaxilla here.

Figure 2. Ocepechelon compared to the soft shell turtle, Trionyx. Bones are relabeled here based on their homology with Trionyx bones. Note the dorsal naris, not close to the original below the naris, but just above the internal naris.

Apparently
Trionyx and Odontochelys were not tested in the original phylogenetic analysis of Bardet et al. 2013, which only used sea turtles in the inclusion set. That taxon exclusion has become a problem with a solution (Fig. 2).

The supplemental data
indicates Bardet et al. used an all-zero hypothetical outgroup and did not include Odontochelys or Trionyx. The supplemental data also includes a short movie of the turtle feeding on a fish, of which here is one frame (Fig. 3). Click here to view the very short movie on YouTube.

Ocepechelon feeding, one frame from the Bardet et al 2013 movie. Click to view on YouTube

A living turtle,
the long-necked mata-mata can be seen here suctioning it prey by expansion of the neck, with a wide open mouth. This is different, of course, from the pipette method used by Ocepechelon. The original purported ‘premaxilla’ is an anterior pair of nasals separated from the posterior pair by a newly opened dorsal set of nares. So rare this may be the only time this has happened for tetrapods.

Postcrania support
the supplemental material of Bardet et al. 2013 reports: “The Maastrichtian Phosphates of the Oulad Abdoun Basin have yielded several very large Chelonioid elements (OCP collection): dorsal shells with large pleural disc fontanelles, widely U-notched and and and indented nuchal, various star-shaped plastral elements with deeply indented edges, shoulder and pelvis (neither protostegid nor dermochelyid) elements, as well as humeri and femurs. All these postcranial elements from Morocco may correspond to Ocepechelon, the only skull morphotype known in the Oulad Abdoun with a corresponding large size. As the skull, none of these postcranial elements can be surely referred to Protostegidae or Dermochelyidae and they could partly belong to Ocepechelon.”

So, the skull of Ocepechelon is not chelonioid, according to the large reptile tree and the disassociated post-crania is not chelonioid, according to the authors. Does anyone else want to look into the possibility that we have a giant soft-shell turtle here? Just add Ocepechelon to a large gamut turtle matrix. Publish the post-cranial bits and pieces. And fix those squamosal/supratemporal issues while you’re at it.

References
Bardet N, Jalil N-E, de Lapparent de Broin F, Germain D, Lambert O, et al. 2013. A Giant Chelonioid Turtle from the Late Cretaceous of Morocco with a Suction Feeding Apparatus Unique among Tetrapods. PLoS ONE 8(7): e63586. doi:10.1371/journal.pone.0063586
Li C, Wu X-C, Rieppel O, Wang L-T and Zhao L-J 2008. An ancestral turtle from the Late Triassic of southwestern China. Nature 456: 497-501.
Gaffney ES 1975. A phylogeny and classification of higher categories of turtles. Bulletin of the American Museum of Natural History 155:387-436.
Meylan PA 1987. The phylogenetic relationships of the soft-shelled turtles (family Trionychidae). Bulletin of the American Museum of Natural History 186:1-101.

wiki/Trionyx
wiki/Odontochelys
wiki/Ocepechelon

Mariliasuchus: a mammal-like croc

Mariliasuchus amarali (Carvalho and Bertini 1999, Zaher et al. 2006, Nobre et al. 2007) is an Early Cretaceous meso-croc with a short skull and mammal like traits.

Figure 1. Mariliasuchus skull in several views. Note the premaxillaery fangs and the short blunt other teeth. Note the postdentary length of the mandible acting as an anchor for powerful muscles. There’s sort of a double lateral fenestra here, also seen in Baurusuchus. The upper lateral temporal fenestra appears between the quadrate and squamosal. 

Distinct from most crocs,
but like most mammals, Mariliasuchus nostrils faced anteriorly. Like most mammals the teeth were divided into incisors, canines and molars, but the canines were on the premaxilla. The incisors were procumbent. Vasconcellos et al. (2002) compared these with the teeth of pigs. Oral processing of the food was evident by the shape of the teeth, the inset of the maxillary teeth (implying lips) and the ability of the the mandible to move back and forth. The mineral composition of coprolites found with the specimens also indicate an omnivorous diet.

Ontogenetic studies
(Vasconcellos and Carvalho 2005) noted skulls became shorter and laterally compressed during growth — but this could be phylogenetic since Mariliasuchus nests at the base of a narrow-skull clade that includes Caipirasuchus and Baurusuchus in the large reptile tree (Fig. 2) and the skull shown here (Fig. 1) is wider than tall. These sisters of Mariliasuchus likewise have anterior nares and Caipirasuchus has blunt teeth with premaxillary canines.

Figure 2. Mariliasuchus nests at the base of a derived clade of narrow-skulled crocs, like its contemporary, Baurusuchus. This is a subset of the large reptile tree. Lewisuchus is a pre-dinosaur.

The postcranial skeleton
includes traits similar to those of Notosuchus and extant crocs. Nobre and Carvalho (2013) thought Mariliasuchus had a sprawling posture like living crocs.

The larger clade that includes Mariliasuchus
also includes the tiny herbivore Simosuchus and that clade is the sister clade to living crocs like Caiman and marine crocs with flippers and tails like Metriorhynchus (Fig. 2).

References
Carvalho IS and Bertini R 1999. Mariliasuchus: um novo Crocodylomorpha (Notosuchia) do Creta´ceo da Bacia Bauru. Geologı´a Colombiana 24: 83–105.
Nobre PH and Souza Carvalho I de 2013. Postcranial skeleton of Mariliasuchus amarali Carvalho and Bertini, 1999 (Mesoeucrocodylia) from the Bauru Basin, Upper Cretaceous of Brazil. Ameghiniana 50 (1): 98–113.
Nobre PH et al. 2007. Mariliasuchus robustus, a new Crocodylomorpha (Mesoeucrocodylia) from the Bauru Basin, Brazil. Anuário do Instituto de Geociências 30 (1): 38–49.
Zaher H et al. 2006. Re-description of the cranial morphology of Mariliasuchus amarali, and its phylogenetic affinities (Crocodyliformes, Notosuchia)”. American Museum Novitates 3512: 1–40.

wiki/Mariliasuchus

New Evolution of Humans Video on YouTube

The origin of mammals from cynodonts is universally accepted.
The origin of humans from primates is universally accepted among paleontologists, not among religious conservatives. Perhaps this short video can help fact check a few misconceptions.

Figure 1. Human evolution video on YouTube. Cllick to view.

Here you’ll see the origin of humans,
and all their many body parts, in a new light. We start with fishy tetrapods, just hitting the beachheads 365 million years ago (mya). By 340 mya the first reptiles were already diversifying. Our lineage goes on from there in a stepwise progression with novel traits appearing with each successive taxon every few million years in the fossil record.

The record is becoming more and more complete.
Using the closest known sister taxa to the actual lineage we can document a gradual accumulation of human traits, both bones and soft tissues, as well as likely behaviors based on phylogenetic bracketing. Here the human lineage runs through the reptilomorphs and seymouriamorphs, the basal reptiles, the synapsids, the therapsids, the cynodonts, the mammals, primates, anthropoids and hominids, only some of which ultimately evolved to become human.

Feel free to pause the video
at any point if scenes change before you finish reading a frame.

Look for other YouTube videos
that document the origin of pterosaurs, dinosaurs and turtles in a similar fashion.

More details and reference materials
can be found at ReptileEvolution.com

Want more?
For the story of human evolution going back through raw chemicals, cells, worms and fish (along with all of the above taxa), read “From the Beginning, the Story of Human Evolution” by David Peters (Little Brown, 1991), a copy of which can be found as a pdf online at www.davidpetersstudio.com/books.htm