Teyujagua paradoxa: still no paradox in the LRT

Back in 2016 Pinheiro et al.
introduced readers to a small Early Triassic proterosuchid without much of an antorbital fenestra, Teyujagua paradoxa (Fig. 1). Back then a smaller large reptile tree (LRT, subset Fig. 2) nested Teyujagua as one of several smaller descendants of Proterosuchus without an antorbital fenestra. Based on taxon exclusion Pinheiro et al. 2016 mistakenly described Teyujagua as, “transitional in morphology between archosauriforms and more primitive reptiles…as the sister taxon to Archosauriformes.” Evidently they were looking for greater glories than Teyujagua actually represented.

Figure 1. Teyujagua compared to sister taxa, including Youngoides, Proterosuchus and Chasmatosaurus. Teyujagua is a phylogenetic miniature in which the antorbital fenestra became a vestige.

Figure 1. Teyujagua compared to sister taxa, including Youngoides, Proterosuchus and Chasmatosaurus. Teyujagua is a phylogenetic miniature in which the antorbital fenestra became a vestige.

 

This year (2019) Pinheiro et al. returned to Teyjagua
They wrote, “The evolution of the archosauriform skull from the more plesiomorphic configuration present ancestrally in the broader clade Archosauromorpha was, until recently, elusive.”

This is a bogus statement.
The LRT found a series of terrestrial younginiforms basal to archosauriforms and protorosauria. You read about them here in 2011. All the authors had to do was google Teyjagua to find the data needed to overturn their hypothesis.

Pinheiro et al. 2019 continue, 
“This began to change with the discovery and description of Teyujagua paradoxa, an early archosauromorph from the Lower Triassic Sanga do Cabral Formation of Brazil. In addition to providing new details of the anatomy of T. paradoxa, our study also reveals an early development of skull pneumaticity prior to the emergence of the antorbital fenestra.”

This is an backwards statement.
The LRT found Teyujagua was losing an antorbital fenestra, not gaining one. Adding taxa would have solved this problem for Pinheiro et al. 2019, as suggested three years ago.

Pinheiro et al. 2019 continue,
‘The data presented here provide new insights into character evolution during the origin of the archosauriform skull.”

The actual origin of the archosauriform skull
according to the LRT (Fig. 2). occurs in a list of excluded taxa ending with Youngoides romeri FMNH UC1528. As before Teyujagua remains a sister to Chasmatosaurus alexandri NMQR 1484 and is therefore a dead end taxon, basal to nothing.

Figure 2. Cladogram of basal archosauriforms. Note the putative basalmost archosauriform, Teyujagua (Pinheiro et al 2016) nests deep within the proterosuchids. The 6047 specimen that Ewer referred to Euparkeria nests as the basalmost euarchosauriform now.

Figure 2. Cladogram of basal archosauriforms. Note the putative basalmost archosauriform, Teyujagua (Pinheiro et al 2016) nests deep within the proterosuchids. The 6047 specimen that Ewer referred to Euparkeria nests as the basalmost euarchosauriform now.

This should be embarrassing to the authors
when an amateur without a science degree of any firsthand access to  the specimen can tell the PhDs they didn’t included enough taxa to understand what they were dealing with. Sadly, this is not the first time, and it won’t be the last. The LRT is a powerful tool, free for all to use.

Figure 1. Youngoides romeri FMNH UC1528 demonstrates an early appearance of the antorbital fenestra in the Archosauriformes. This specimen is the outgroup to Proterosuchus, the traditional basal member of the Archosauriformes. 

Figure 3. Youngoides romeri FMNH UC1528 demonstrates an early appearance of the antorbital fenestra in the Archosauriformes. This specimen is the outgroup to Proterosuchus, the traditional basal member of the Archosauriformes.

Figure 3. Click to enlarge. Updated image of various proterosuchids and their kin. When you see them all together it is easier to appreciated the similarities and slight differences that are gradual accumulations of derived taxa.

Figure 4. Click to enlarge. Updated image of various proterosuchids and their kin. When you see them all together it is easier to appreciated the similarities and slight differences that are gradual accumulations of derived taxa. Teyujagua is a deadened taxon, less glorious than Pinheiro et al. 2016 and 2019 wish it was.

A paper on Youngoides romeri and the origin of the Archosauriformes
can be read online here at ResearchGate.org. It was rejected by the referees.


References
Pinheiro FL, França MAG, Lacerda MB, Butler RJ and Schultz CL 2016. An exceptional fossil skull from South America and the origins of the archosauriform radiation. Nature Scientific Reports 6:22817 DOI: 10.1038/srep22817.
Pinheiro FL, De Simao-Oliveira D and Butler RJ 2019. Osteology of the archosauromorph Teyujagua paradoxa and the early evolution of the archosauriform skull.
Zoological Journal of the Linnean Society, zlz093
https://doi.org/10.1093/zoolinnean/zlz093
https://academic.oup.com/zoolinnean/advance-article-abstract/doi/10.1093/zoolinnean/zlz093/5585773

https://pterosaurheresies.wordpress.com/2016/03/13/teyujagua-not-transitional-between-archosauriforms-and-more-primitive-reptiles/

 

New Triassic basal dimorphodontid: Caelestiventus

Britt, et al. 2018
bring us a new desert-dwelling Triassic pterosaur, Caelestiventus hanseni (Figs. 1, 2; BYU 20707, Museum of Paleontology at Brigham Young University) from western North America. They nest it with Dimorphodon (Fig. 1), from the English Jurassic, although Preondactylus (Fig. 3) is also similar, with a huge naris, and also from the Late Triassic. Caelestiventus is larger than most Triassic pterosaurs, with a wingspan of at least 1.5 meters. Coeval Raeticodactylus is similar in size and also fills in the lower orbit with a thin sheet of bone.

Britt, et al. also confirm the nesting
of ‘Dimorphodon’ weintraubi with anurognathids, something first published by Peters 2011 and reported here the same year.

Unfortunately
Britt and colleagues nest anurognathids as the sister taxa to Dorygnathus due to taxon exclusion. In the large pterosaur tree (LPT, 234 taxa) anurognathids nest with and arise from dimorphodontids. Among the many taxa missing from the Britt et al. tree is the IVPP giant embryo anurognathid, a completely preserved specimen, and Mesadactylus, another Jurassic transitional sister basal to anurognathids… also from North America.

Figure 1. Triasic Caelestiventus skull compared to Jurassic Dimorphodon. Readers, don't do the easy thing and go to the Wellnhofer diagrams for your pterosaur skulls. Use real data.

Figure 1. Triasic Caelestiventus skull compared to Jurassic Dimorphodon. Readers, don’t do the easy thing and go to the Wellnhofer diagrams for your pterosaur skulls. Use real data.

It’s always wonderful to see a new pterosaur taxon.
Congratulations to all coauthors on this paper.

Figure 4. The skull of Bergamodactylus (MPUM 6009)

Figure 2. The skull of Bergamodactylus (MPUM 6009) the most primitive pterosaur in the LPT.  No antorbital fossa here and not tested by Britt et al.

The sculptor of the skull
(Fig. 1) put a ‘Roman nose’ on the restoration of Caelestiventus. That illustration will float around the paleo-universe forever. However, I take my cue from the Triassc age of the specimen and the downturned dentary, as in the Triassic basalmost pterosaur, Bergamodactylus (Fig. 2), which has an unexpanded naris, to create a more transitional naris (Fig. 1), and from Preondactylus (Fig. 3), a closer relative with a large, yet straight naris, rather than create a derived version with more of a curve than Dimorphodon had.

Figure 3. Preondactylus from the Late Triassic is basal to Dimorphodon in the LPT.

The staff or hired artist
charged with illustrating Caelestiventus in vivo (Fig. 4) made a few mistakes. These were generated, no doubt, by the many false paradigms floating around out there. Here they are shown and corrected. (Just found out the artist is Michael Skrepnick, Dinosaursinart.com)​

  1. The manual claws should point down toward the palm, as in most tetrapods
  2. Pedal digit 5 should be on the lateral side of a much larger foot and it should not be involved in the uropatagia.
  3. The tail should be shorter if closer to Dimorphodon than to Preondactylus. Otherwise it might be that long.
  4. The rostrum is straight inLate Triassic sister, Preondactylus, so  perhaps a straight angled rostrum is more appropriate here.
  5. The wing membranes were stretched between elbow and wing tip, as all soft tissue pterosaur fossils demonstrate.
  6. The cranium probably tipped down posteriorly, as all related taxa demonstrate (Figs. 1–3).
Figure 2. Pity the poor staff artist trying to get a pterosaur correct in today's climate. Here the original and revised morphologies are presented.

Figure 4. Pity the poor staff artist trying to get a pterosaur correct in today’s climate. Here the original and revised morphologies are presented. Digit 5 need to go to the outside of a large foot and the tail is short.

Perhaps hoping to support the invalid archosaur origin of pterosaurs hypothesis,
Britt et al report the margin of an antorbital fenestra bears a remnant of a fossa. We looked at a similar interpretation earlier when Nesbitt and Hone 2010 attempted to pull a Larry Martin with that single trait from Dimorphodon. Thankfully, Britt et al. did not attempt to use Euparkeria or any phytosaurs for outgroups. But, regrettably, they didn’t use Cosesaurus either (Fig. 5). Avoiding further controversy, they left the basalmost node generic: “Pterosauria”.

Addendum: checking the SuppMat .nex file,
I see they employed the tritiosaur lepidosaur, Macrocnemus, and two large archosauriforms, Postosuchus and Herrerrasaurus for outgroup taxa. That still does not get you very far based on the verified and validated taxa listed below. Neither Postosuchus nor Herrerasaurus are related to Macrocnemus and pterosaurs.

Figure 5. Basal pterosaurs in the LPT.

Figure 5. Basal pterosaurs and their outgroups in the LPT.

Late addendum
Adding Caelestiventus to the LPT nests it basal to the Dimorphodon clade, not with Dimorphodon.

Figure 1. Maxilla, nasal and jugal of Caeletiventus, plus full mandible.

Figure 1. Maxilla, nasal and jugal of Caeletiventus, plus full mandible casts created by CT scans. Colors added here.

References
Britt BB, Dalla Vecchia FM, Chure DJ, Engelmann GF, Whiting MF, and Scheetz RD 2018. Caelestiventus hanseni gen. et sp. nov. extends the desert-dwelling pterosaur record back 65 million years. Nature Ecology & Evolutiondoi:10.1038/s41559-018-0627-y.
Nesbitt SJ and Hone DWE 2010. An external mandibular fenestra and other archosauriform character states in basal pterosaurs. Palaeodiversity 3: 225–233
Peters D 2011. A Catalog of Pterosaur Pedes for Trackmaker Identification
Ichnos 18(2):114-141. http://dx.doi.org/10.1080/10420940.2011.573605

https://en.wikipedia.org/wiki/Caelestiventus

A new view of the first archosauriform antorbital fenestra

Earlier we looked at the FMNH UC 1528 specimen of Youngoides romeri. Today we’ll see another view of the same specimen in a GIF movie (Fig. 1). The antorbital fenestra identified here has been overlooked for several decades.

Figure 1. GIF movie tracing the antorbital fenestra with fossa and surround bones of the FMNH UC 1528 specimen of Youngoides romeri. This is one of the earliest and most primitive appearances of the archosauriform antorbital fenestra, previously overlooked.

Figure 1. GIF movie tracing the antorbital fenestra with fossa and surround bones of the FMNH UC 1528 specimen of Youngoides romeri. This is one of the earliest and most primitive appearances of the archosauriform antorbital fenestra, previously overlooked.

Youngoides romeri FMNH UC1528 (Olson and Broom 1937) Late Permian, Wuchiapingian, ~255 mya was derived from a sister to Youngina AMNH 5561 and preceded Proterosuchus at the base of the Eurchosauriformes.

This nesting of Youngina and Youngoides at the base of the Protorosauria and Archosauriformes is recovered in the large reptile tree. Prior studies tended to include squamates close to this node, but the large reptile tree found squamates nesting on a completely separate branch with a last common ancestor at the origin of the Amniota/Reptilia.

References
Olson EC and Broom R 1937. New genera and species of tetrapods from the Karroo Beds of South Africa. Journal of Paleontology 11(7):613-619

wiki/Youngina

Evolution basics – starring Jon Stewart and Babe Ruth

Evolution does not work in mysterious ways.
The basics (small variations leading over dozens of generations to larger changes) are simple:

GIF movie 1. Skull width as a variable demonstrated by Babe Ruth and John Stewart in this animated GIF file.

GIF movie 1. Skull width as a variable demonstrated by Babe Ruth and John Stewart in this animated GIF file.

  1. wider / narrower (skull, body, feet, etc.)
  2. taller-larger / smaller-shorter
  3. longer (more ribs) / shorter (fewer ribs)
  4. longer limbs / shorter limbs
  5. larger skull / smaller skull
  6. longer preorbital region / longer postorbital region
  7. longer neck / shorter neck
  8. sharp claws / rounded claws
  9. etc. / etc.

At left 
are extinct baseball star, Babe Ruth, and extant comedian/commentator, Jon Stewart, graphically demonstrating #1 on the above list, wider / narrower in the skull shape. Both are male members of the species Homo sapiens.

Other traits
one can add to this list include various perforations or fenestrae (which have several and often convergent origins and disappearances:

  1. fenestra between the naris and orbit (antorbital fenestra)
  2. fossa surrounding antorbital fenestra
  3. one or more fenestrae between the orbit and occiput
  4. fenestra in the mandible
  5. occipital fenestrae expand over braincase
  6. acetabulum perforated or not

And once fenestrae are formed:

  1. Loss of lower temporal arch
  2. Loss of upper temporal arch
  3. Loss of both

Then add
the size and shape of various bones and their processes compared to other bones and you have yourself a long character list. Enough of these (150+) provide a good matrix of characters and character states that can produce the menagerie of reptiles found in the large reptile tree, now numbering 566 taxa for 228 characters.

The wider / narrower and smaller / larger dichotomies 
can also be seen in the variety of specimens attributed to Proterosuchus and Chasmatosaurus (Fig. 2, Broom 1903). Some paleontologists (Welman 1998, Ezcurra  and Butler 2015) consider these taxa congeneric. They think this variety constitutes an ontogenetic series. On the other hand, the large reptile tree recovered these taxa in distinct nodes and clades. Narrower-skulled forms nest together. So do wider-skulled forms and they lead to other even more distinct taxa, including some once again tiny forms. The tall-skulled proterosuchids do not lead to more derived taxa.

Figure 3. The many faces of Proterosuchus to scale and in phylogenetic order, among with their closest known relatives. Note the phylogenetic miniaturization, reduction of the drooping premaxilla and loss of the antorbital fenestra after the TM 201 specimen of Chasmatosaurus. Click to enlarge.

Figure 2. The many faces of Proterosuchus to scale and in phylogenetic order, among with their closest known relatives. Note the phylogenetic miniaturization, reduction of the drooping premaxilla and loss of the antorbital fenestra after the TM 201 specimen of Chasmatosaurus. Click to enlarge.

The smallest taxon
shown here (Fig. 2), Youngoides romeri, leads to euparkeriids and then to a long list of archosauriforms including dinosaurs, crocs and birds. This last common ancestor of proterosuchids and euparkeriids (all archosauriforms) also had a small antorbital fenestra.

Have a great weekend!
Keep those cards and letters coming.

References
Broom R. 1903. On a new reptile (Proterosuchus fergusi) from the Karroo beds of Tarkastad, South Africa. Annals of the South African Museum 4: 159–164.
Ezcurra MD and Butler RJ 2015. Post-hatchling cranial ontogeny in the Early Triassic diapsid reptile Proterosuchus fergusi. Journal of Anatomy. Article first published online: 24 APR 2015. DOI: 10.1111/joa.12300
Welman J 1998. The taxonomy of the South African proterosuchids (Reptilia, Archosauromorpha). Journal of Vertebrate Paleontology 18 (2): 340–347.

The antorbital and lateral temporal fenestrae of the frog , Rana

Earlier we looked at the evolution of the frog, Rana. And it continues to be the most popular blog post of the past year.

Today, after adding Rana to the matrix of the large reptile tree (still not updated), I think it’s time we looked at the antorbital fenestra of Rana, and the lateral temporal fenestra as well (Fig. 1).

Figure 1. Rana, the bull frog, with naris in red, orbit in purple, antorbital fenestra in dark blue and lateral temporal fenestra in orange. The reduction of the the skull bones in Rana created these fenestrae.

Figure 1. Rana, the bull frog, with naris in red, orbit in purple, antorbital fenestra in dark blue and lateral temporal fenestra in orange. The reduction of the the skull bones in Rana created these fenestrae.

One usually thinks of additional skull fenestrae in the province of reptiles. As we saw earlier, the antorbital fenestra comes and goes in several reptiles. So does the lateral temporal fenestra. Amphibians (non-amniote tetrapods) typically do not have skull fenestrae. Neither to most basal reptiles.

Relative to the body, the skull of Rana is enormous. So are the hind limbs. Frogs leap, as everyone knows, and if the skull is going to be large it also has to be lightweight to enable longer leaps. So the skull bones are reduced to their bare minimum creating fenestrae.

Proximal outgroup taxa, including long-legged Triadobatrachus, likewise have reduced skull bones.

More distant outgroup taxa, including short-legged Gerobatrachaus and Doleserpeton and Utegenia have relatively smaller skulls and shorter hind limbs — and no skull fenestrae.

 

 

A closer look at the “antorbital fossa” in two pterosaurs, Raeticodactylus and Dimorphodon

Nesbitt and Hone (2010) broke with tradition to propose that certain pterosaurs had a mandibular fenestra. We discussed this mistake earlier. Now we are going to look at another one of their other futile grasps at the archosaur straw, a purported antorbital fossa in Dimorphodon (Figs. 1, 2) and Raeticodactylus (Fig. 3). An antorbital fossa is not found in ANY other pterosaur. And the two examples they propose don’t match each other in any way or fashion. So, ironically, Nesbitt and Hone (2010) were acting as heretics and I am here to hold the traditional line.

From Nesbitt and HONE 2010, a purported antorbital fossa in Dimorphodon. Note where it is. This strut support is a little thinner and therefore a little deeper than the rest of the ascending process. Dimorphodon depresses this area more than other pterosaurs.

Figure 1. From Nesbitt and Hone 2010, a purported antorbital fossa in Dimorphodon. Note where it is compared to figure 3 (below). This triangular strut support is a little thinner and therefore a little deeper than the rest of the cylindrical ascending process. Dimorphodon depresses this area more than other pterosaurs, like Eudimorphodon.  This also may be due to crushing, similar to the crushing surrounding each tooth. Oops. Yeah, there it is…

Figure 2. the jugal of Dimorphodon adds depth to the tooth-bearing portion of the maxilla, adding to the impression of an antorbital fossa.

Figure 2. The jugal of Dimorphodon adds depth to the tooth-bearing portion of the maxilla, adding to the impression of an antorbital fossa, a fact overlooked by Nesbitt and Hone (2010).

Dimorphodon has one of the largest and lightest skulls of any early Jurassic or Triassic pterosaur. The nasal, antorbital and orbital fenestra made up the vast majority of the skull separated by the thinnest struts of bone in the Pterosauria. Like any good engineer Dimorphodon supported its grid-like struts with small triangles of bone, like the one at the base of the slender ascending process of the maxilla. Paper thin, this triangular support at the base of the cylindrical ascending process was identified as an antorbital fossa by Nesbitt and Hone (2010). No other pterosaur depresses, or thins this area, which may be thinner due to crushing. Note the areas between the maxillary teeth, which exhibit similar crushing. Nesbitt and Hone (2010) also failed to note the presence of the laminated jugal (Fig. 2), which adds depth to the tooth-bearing portion of the maxilla.

Raeticodactylus skull. Nesbitt and Hone (2010) say the red areas represent the antorbital fossa.

Figure 2. Raeticodactylus skull. According to Nesbitt and Hone (2010) the red areas represent the antorbital fossa. Here these areas are interpreted as the transverse width of the  girder-like ascending process (stronger to support that rhino-like horn when it’s called into action), and otherwise typically buried in the matrix. At the top the transverse lacrimal is equally wide in the Z-axis. Note the ventral view of the skull (in blue, twisted during crushing) that confirms we’re seeing the ventral aspect of the maxilla/lacrimal portion of the antorbital fenestra. Also note this purported antorbital fossa is not the same as that seen in Dimorphodon (Fig. 1). No homology here.

Raeticodactylus was also promoted by Nesbitt and Hone (2010) as having an antorbital fossa, but there’s no basal triangular support for the maxillary ascending process here. So the two do not reflect homologous morphologies (which should have raised a red flag, except they were so hell-bent on providing “evidence” for an archosaur connection they ignored or overlooked this key fact). Instead what we’re seeing is the crushed transverse width of the girder-like ascending process of the maxilla and the ventral aspect of the lacrimal and skull roof. The skull had to be stronger than a typical pterosaur skull. After all it was doing something with that rhino-like horn and this reinforcement tells us it wasn’t just for display~!

Bottom line: No mandibular fenestra. No antorbital fossa. Pterosaurs are not archosaurs.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Buckland W 1829. Proceedings of the Geological Society London, 1: 127
Owen R 1859. On a new genus (Dimorphodon) of pterodactyle, with remarks on the geological distribution of flying reptiles.” Rep. Br. Ass. Advmnt Sci., 28 (1858): 97–103.
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. online pdf
Nesbitt SJ and Hone DWE 2010. An external mandibular fenestra and other archosauriform character states in basal pterosaurs. Palaeodiversity 3: 225–233
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.
Sangster S 2001. Anatomy, functional morphology and systematics of Dimorphodon. Strata 11: 87-88

wiki/Dimorphodon