Hey! Some of those Miocene ‘ungulates’ are marsupials!

More heresy today
courtesy of taxon inclusion.

Cassini 2013
looked at several traditional Miocene South American ‘ungulates’ (Fig. 1) unaware that these taxa do not nest in monophyletic clade any more specific than Theria in the large reptile tree (LRT, 1401 taxa). Cassini was reporting the results of “an ecomorphological study based on geometric morphometrics of the masticatory apparatus.” So he was working from prior cladograms and focusing on the mechanics of eating.

Figure 1. Image from Cassini 2013. Pink taxa are marsupials. Others are placentals.

Figure 1. Image from Cassini 2013. Pink taxa are marsupials. Others are placentals.

Earlier
here and here the traditional clade Notoungulata was splintered by the LRT into several clades, some among the marsupials, other among the placentals.

Traditional ‘Litopterna’
Diadiaphorus (Fig. 1) nests at the base of this clade. Theosodon (Fig. 1) nests as a derived taxon. Also included, but not listed: Chalicotherium and other chalicotheres.

Considering its member taxa,
the clade Litopterna (Ameghino 1889) is a junior synonym for Chalicotheridae (Gill 1872) in the LRT.

Considering its member taxa,
the clade Astrapotheria (Lydekker 1894) is a junior synonym for Meniscotheriinae (Cope 1882) and both nest within Phenacodontidae (Cope 1881).

Interatheriidae (Ameghino 1887) traditionally includes Interatherium, Protypotherium, Miocochilius and other taxa listed here. In the LRT Interatherium nests close to the ancestry of the Toxodon clade + the kangaroo clade within Metatheria. By contrast, Protypotherium and Miocochillus nest with Homalodotherium deep within the Eutheria. Homalodotherium traditionally nests with the the metatherian Toxodon. According to the LRT, all the above taxa developed similar enough traits by convergence that all were mistakenly lumped together in the invalid placental clade ‘Notoungulata’.

This is not the first time
metatherians were split from convergent eutherians. Most creodonts are marsupial predators, phylogenetically distinct from their traditional sisters in the clade Carnivora, within the clade Eutheria (Placentalia).

New taxa added to the LRT:

  1. Hegetotherium (Fig. 1) nests with Mesotherium between Interatherium and the Toxodon clade in the Metatheria. 
  2. Diadiaphorus (Fig. 1), the horse-mimic, nests at the base of the Litopterna/Chalicotheriidae, just basal to Litolophus.

I did not know these two, so I added these two to better understand them.

References
Cassini G 2013. Skull Geometric Morphometrics and Paleoecology of Santacrucian (Late Early Miocene; Patagonia) Native Ungulates (Astrapotheria, Litopterna, and Notoungulata). Ameghiniana 50 (2):193–216. DOI: 10.5710/AMGH.7.04.2013.606

Cosesaurus vs. Saller 2016 part 2

Yesterday we looked at
some typically and recently overlooked pterosaur traits in Cosesaurus, a lepidosaur, tritosaur, tanystropheid, fenestrasaur taxon that nests as a pterosaur outgroup in the large reptile tree (LRT, 1401 taxa). Saller 2016 reported a lack of pterosaur traits in his examination of Cosesaurus beneath a microscope. Since Cosesaurus is so small, lacks bones and is printed as a negative in the matrix (holes become bumps), this specimen is best viewed on a computer monitor after dozens of close-ups have been taken using various angles of lighting to bring out one detail or another.

Today we’ll finish examining Cosesaurus
by taking a DGS look at the extremities and soft tissue. GIF animations trace what I see and allow you to see (or not see) pertinent impressions in the grainy matrix.

Figure 1. Cosesaurus skull frills and gular sac.

Figure 1. Cosesaurus skull frills and gular sac. I did not trace all the dorsal frills. Perhaps you’ll see several more near the base of the skull.

First a little backstory

Yang et al. 2018 considered pterosaur plumage/fibers homologous with dinosaur/bird feathers—but only by omitting fenestrasaurs like Cosesaurus, Sharovipteryx and Longisquama (Fig. 9), all of which preserve feathery/hairy fibers covering their bodies. We looked at that issue here. At the end of that post, it is worthwhile to review what several pterosaur experts opined on that issue. None reminded us that Cosesaurus and kin were closer relatives of pterosaurs, developing extradermal membranes and plumage by convergence, though all were aware of this hypothesis of relationships.

Figure 2. Cosesaurus nasal crest (in yellow).

Figure 2. Cosesaurus nasal crest (in yellow).

Figure 3. Cosesaurus dorsal frill. This frill evolves into giant plumes on another Cosesaurus descendant, Longisquama.

Figure 3. Cosesaurus dorsal frill. This frill evolves into giant plumes on another Cosesaurus descendant, Longisquama. Image from Ellenberger 1993. This appears to  be a fluorescing image.

The dorsal frill of Middle Triassic Cosesaurus
(Figs. 3, 9) finds its greatest expression in Late Triassic Longisquama (Fig. 9), which was named for its long plumes. The relationship Cosesaurus has with Longisquama has also been largely ignored for the last twenty years.

Figure 4. Cosesaurus uropatagium. This trait is recorded on pterosaurs, Sharovipteryx and Longisquama.

Figure 4. Cosesaurus uropatagium. This trait is recorded on pterosaurs, Sharovipteryx and Longisquama. As in Sharovipteryx some fibers extend anteriorly the femur. See if you can see them without my help.

The twin uropatagia of Middle Triassic Cosesaurus
predates similar extradermal membranes on Late Triassic Sharovipteryx and all pterosaurs (even Sordes, which has been traditional and mistakenly given a single uropatagium spanning both hind limbs, disconnected from the tail). Note the uropatagium extend to p5.1 in Cosesaurus, to p5.2 in the obligate biped, Sharovipteryx, and only the tarsus in pterosaurs, which have a much smaller set of uropatagia, but a larger set of forelimb wings.

Figure 5. Cosesaurus forelimb with pro to-aktinofibrils trailing the ulna.

Figure 5. Cosesaurus forelimb with pro to-aktinofibrils trailing the ulna. DGS enables the tracing of each hand on a segregated/separate Photoshop layer.

Saller 2016
reported none of these tissues and declared that he could see no pterosaur traits in Cosesaurus. This was picked up by the author of the Wikipedia Cosesaurus page as the latest thinking on this specimen, even though it actually represents only one PhD candidate’s opinion. See how important it is to at least attempt to color trace what one sees on a computer monitor? Some things are just too jumbled and/or too subtle to be ‘seen’ by an eyeball or through a microscope. The DGS method, like cladistic analysis, forces one to thoroughly examine and dissect the data into tiny discrete and segregated bits that can be later analyzed and compared.

Figure 6. Cosesaurus hind limbs. The upper one is exposed on the fossil. The lower one is preserved beneath the medusa. The tarsals are not displaced in the latter.

Figure 6. Cosesaurus hind limbs. The upper one is clearly exposed on the fossil (see Figure 4). The yellow dot is a fossilized air bubble. The lower one is preserved beneath the medusa. The tarsals are not quite as displaced in the latter.  These pedes match occasionally bipedal Rotodactylus tracks.

You decide
whether or not these various soft tissues are present in Cosesaurus. I present and interpret the data. All discoveries must be confirmed or refuted by others.

Figure 7. Cosesaurus forelimb fibers. These indicate the pterosaur wing originated distally, as in bird feathers, not as a bat-like membrane arising from the torso.

Figure 7. Cosesaurus forelimb fibers. These indicate the pterosaur wing originated distally, as in bird feathers, not as a bat-like membrane arising from the torso.

Dorsal frills are elaborated
in Longisquama. Uropatagia are elaborated in Sharovipteryx. Aktinofibrils are elaborated in pterosaurs like Bergamodactylus, which is similar in size to Cosesaurus (Fig. 8). These indicate the pterosaur wing originated distally (Peters 2002), as in bird feathers, not as a bat-like membrane arising from the torso.

Figure 1. Bergamodactylus compared to Cosesaurus. Hypothetical hatchling also shown.

Figure 8. Bergamodactylus compared to Cosesaurus. Hypothetical hatchling also shown.

Figure 3. The origin of pterosaurs now includes Kyrgyzsaurus, nesting between Cosesaurus and Sharovipteryx.

Figure 9. The origin of pterosaurs from tanystropheid ancestors now includes Kyrgyzsaurus, nesting between Cosesaurus and Sharovipteryx. Click to enlarge.

Remember
this data was submitted for publication, but rejected, as this hypothesis of relationships continues to be ignored and rejected by pterosaur workers content with the status quo supported by taxon exclusion. That’s why PterosaurHeresies and ReptileEvolution.com continue to document discoveries and post updates nearly every day for the past seven years.


References
Ellenberger P and de Villalta JF 1974. Sur la presence d’un ancêtre probable des oiseaux dans le Muschelkalk supérieure de Catalogne (Espagne). Note preliminaire. Acta Geologica Hispanica 9, 162-168.
Ellenberger P 1978. L’Origine des Oiseaux. Historique et méthodes nouvelles. Les problémes des Archaeornithes. La venue au jour de Cosesaurus aviceps (Muschelkalk supérieur) in Aspects Modernes des Recherches sur l’Evolution. In Bons, J. (ed.) Compt Ren. Coll. Montpellier 12-16 Sept. 1977. Vol. 1. Montpellier, Mém. Trav. Ecole Prat. Hautes Etudes, De l’Institut de Montpellier 4: 89-117.
Ellenberger P 1993. Cosesaurus aviceps . Vertébré aviforme du Trias Moyen de Catalogne. Étude descriptive et comparative. Mémoire Avec le concours de l’École Pratique des Hautes Etudes. Laboratorie de Paléontologie des Vertébrés. Univ. Sci. Tech. Languedoc, Montpellier (France). Pp. 1-664.
Peabody FE 1948.  Reptile and amphibian trackways from the Lower Triassic Moenkopi formation of Arizona and Utah.  University of California Publications, Bulletin of the  Department of Geological Sciences 27: 295-468.
Peters D 2000a. Description and Interpretation of Interphalangeal Lines in Tetrapods.  Ichnos 7:11-41.
Peters D 2000b. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.
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.
Saller F 2016. Anatomia, paleobiologia e filogenesi di Macrocnemus bassanii Nopcsa 1930 (Reptilia, Protorosauria). Alma Mater Studiorum – Università di Bologna Dottorato di Ricerca in Scienze della Terra Ciclo XXVII 206pp.
Sanz JL and López-Martinez N 1984. The prolacertid lepidosaurian Cosesaurus aviceps Ellenberger & Villalta, a claimed ‘protoavian’ from the Middle Triassic of Spain. Géobios 17: 747-753.
Wild R 1993. A juvenile specimen of Eudimorphodon ranzii Zambelli (Reptilia, Pterosauria) from the upper Triassic (Norian) of Bergamo. Rivisita Museo Civico di Scienze Naturali “E. Caffi” Bergamo 16: 95-120.
Yang et al. (8 co-authors) 2018. Pterosaur integumentary structures with complex feather-like branching. Nature ecology & evolution doi:10.1038/s41559-018-0728-7

wiki/Cosesaurus

Peters D xxxx. Unpublished paper on Cosesaurus, Sharovipteryx and Longisquama on ResearchGate.net

Cosesaurus vs. Saller 2016

Nobody wants Cosesaurus aviceps to be a pterosaur ancestor.
Everyone in paleo prefers pterosaurs to be closely related to dinosaurs and their last common ancestor, which is, according to Nesbitt 2011, a phytosaur. This is continually ‘proved’ in pterosaur studies by excluding Cosesaurus (e.g. Hone and Benton 2007, 2009; Benton 1999; Nesbitt 2011) and in Cosesaurus studies by omitting pterosaurs (e.g Saller dissertation 2016). Saller 2016 claims to not see pterosaur traits in Cosesaurus (Fig. x). That is because Saller did not include pterosaurs in his analysis.

Whoever is writing the Wikipedia page on Cosesaurus accepts Saller’s freehand interpretation (Fig. 1) and prefers Saller’s refusal to add pterosaurs to his cladogram. We talked about putting metaphorical ‘blinders’ on earlier.

Figure 1. Cosesaurus insitu. No bones are present. This is a natural mold that includes an amorphous blob, a jellyfish, that trapped one foot of this unique specimen.

Figure x. Cosesaurus insitu. No bones are present. This is a natural mold that includes an amorphous blob, a jellyfish, that trapped one foot of this unique specimen. This is about natural size.

Today we’ll take another look
at the tiny mold fossil that is Cosesaurus. It preserves a nearly completely articulated tiny lepidosaur tritosaur tanystropheid fenestrasaur (according to the large reptile tree, LRT, 1401 taxa) so sensitively preserved that it shares the matrix with an amorphous medusa (jellyfish) clearly presented.

Saller (p.148) wrote (Google translated from the original Italian):
“At the base of the orbit there is a depression that has been interpreted as a window  antorbital from Ellenberger (1977) and from Peters, which even distinguishes three antidotal windows (Peters, 2000). While the presence of a depression is certain, the conditions of conservation and the difficulty in identifying the sutures among the various elements makes it difficult to propose one of his own reliable interpretation. If it were really an antorbital window, this circumstance, together with the poor development of the subnarial process of the premaxillary, they would be elements a support of the hypothesis of an affinity with the pterosaurs.” 

Is an antorbital fenestra present in Cosesaurus?
Saller said he saw only a depression. You decide by examining these several pictures of the skull of Cosesaurus in various lighting angles (Fig. 1).

Figure 1. The skull of Cosesaurus traced using DGS methods and lit at various angles. Some of these are negatives of a negative mold, giving a positive view. Saller was not sure about the antorbital fenestra, probably because it is represented by an elevated portion in the mold.

Figure 1. The skull of Cosesaurus traced using DGS methods and lit at various angles. Some of these are negatives of a negative mold, giving a positive view.  See how they change, revealing new details? Black dot is a fossil air bubble. Judge for yourself whether or not you see an antorbital fenestra here. Compare this skull with Bergamodactylus, the basalmost Triassic pterosaur.

We must let Saller 2016 finish his thought (from above):
The analysis of the postcranial skeleton [of Cosesaurus] offers however, very little space for this interpretation.” So, Saller denies or discounts what he sees on the rostrum, because he does not see pterosaur traits in the post-crania. [ Hello, Larry Martin! ] Even so, by not including any pterosaurs in his cladogram, Saller fails to test the possibility that just an antorbital fenestra is enough to make Cosesaurus a transitional taxon basal to pterosaurs.

Don’t drop the ball when you’re just about to make a touchdown.
Was PhD candidate Saller advised to not test pterosaurs in his cladogram? I’d like to find out. 

If the post-crania is Saller’s only anti-pterosaur issue, 
let’s take another look at the various post-cranial pterosaur traits found in
Cosesaurus that Saller did and didnot see. It will help to segregate them using DGS methodology.

Figure 2. Cosesaurus torso and forelimbs. The hot pink stem-like coracoids are found in pterosaurs. So are the strap-like scapula, distinct from the discs found in Macrocnemus. There is a close association of the clavicles, interclavicle and sternum. In pterosaurs this is known as a sternal complex.

Figure 2. Cosesaurus torso and forelimbs. The hot pink stem-like coracoids are found in pterosaurs. So are the strap-like scapula, distinct from the discs found in Macrocnemus. There is a close association of the clavicles, interclavicle and sternum. In pterosaurs this is known as a sternal complex. Note how the humerus disappears when the lighting angle changes. That little sphere is a fossilized air bubble. Yellow frills are feathery, pro-aktintofibrils. 

Some data are hard to ‘see’ even under a microscope.
Some data need to be visually segregated in order to see what is really going on in a fossil. Saller gives no indication that he traced any portion of Cosesaurus for his dissertation. Nor did he create a negative of the negative mold. I can tell you from leaning over a microscope looking at Cosesaurus in Barcelona, it is impossible to comprehend this specimen without creating a positive and using tracings to help simplify and segregate elements on a computer monitor. Saller did not use all the tools at his disposal. Neither did I while writing Peters 2000. Now I know better.

Here (Fig. 2) DGS methods segregate the pectoral elements from the ribs and gastralia. The coracoids have a curved stem, as in the Triassic pterosaur, Bergamodactylus— distinct from the discs in more basal tritosaurs/tanystropheids. The sternum, interclavicle and clavicles are coincident and just about to fuse in Cosesaurus, creating a sternal complex, as in pterosaurs—distinct from more basal tritosaurs/tanystropheids. Saller 2016 did not see this.

Saller reports he did see the strap-like scapulae, distinct from the discs found in Macrocnemus… and even though the pterosaur traits keep adding up by Saller’s own admission, still that was not enough to add pterosaurs to his cladogram. Is this an example of peer-group pressure?

Why does the humerus disappear
when the lighting angle is moved (Fig. 2)? Because it is crushed upon the dorsal vertebrae. Only certain lighting angles reveal the right humerus. Why does it crush so completely? Because it is hollow. Can you name another small Triassic reptile with extremely hollow arm bones?

Figure 3. The pelvis of Cosesaurus with prepubis in green and 5 sacrals, not 2 as Saller interprets the fossil.

Figure 3. The pelvis of Cosesaurus with prepubis in green and 5 sacrals, not 2 as Saller interprets the fossil.

Saller 2016 looked at the pelvis
and reported only two sacrals present, despite the long ilium he noted. There are five sacrals in Cosesaurus. Sacral are added in response to a bipedal stance — needed whenever flapping its arms (remember the stem-like coracoid is the clue to this behavior).

Saller failed to see the prepubes. One is pretty obvious here (Fig. 3 in green), but I missed it, too prior to writing Peters 2000.  Prepubes add anchors for femoral adduction, which happens when the knees are brought closer to the midline, typically for bipedal locomotion.

More pterosaur traits tomorrow. 


Just in time—a pertinent quote from Dr. John Ostrom,
“With the announcement of the first dinosaurs with feathers from China, Ostrom (then age 73) was in no mood to celebrate. He is quoted as saying‘I’ve been saying the same damn thing since 1973, `I said, `Look at Archaeopteryx!’” 


References
Ellenberger P and de Villalta JF 1974. Sur la presence d’un ancêtre probable des oiseaux dans le Muschelkalk supérieure de Catalogne (Espagne). Note preliminaire. Acta Geologica Hispanica 9, 162-168.
Ellenberger P 1978. L’Origine des Oiseaux. Historique et méthodes nouvelles. Les problémes des Archaeornithes. La venue au jour de Cosesaurus aviceps (Muschelkalk supérieur) in Aspects Modernes des Recherches sur l’Evolution. In Bons, J. (ed.) Compt Ren. Coll. Montpellier 12-16 Sept. 1977. Vol. 1. Montpellier, Mém. Trav. Ecole Prat. Hautes Etudes, De l’Institut de Montpellier 4: 89-117.
Ellenberger P 1993. Cosesaurus aviceps . Vertébré aviforme du Trias Moyen de Catalogne. Étude descriptive et comparative. Mémoire Avec le concours de l’École Pratique des Hautes Etudes. Laboratorie de Paléontologie des Vertébrés. Univ. Sci. Tech. Languedoc, Montpellier (France). Pp. 1-664.
Kellner AWA 2015. Comments on Triassic pterosaurs with discussion about ontogeny and description of new taxa. Anais da Academia Brasileira de Ciências (2015) 87(2): (Annals of the Brazilian Academy of Sciences) Printed version ISSN 0001-3765 / Online version ISSN 1678-2690.
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.
Peabody FE 1948.  Reptile and amphibian trackways from the Lower Triassic Moenkopi formation of Arizona and Utah.  University of California Publications, Bulletin of the  Department of Geological Sciences 27: 295-468.
Peters D 2000a. Description and Interpretation of Interphalangeal Lines in Tetrapods.  Ichnos 7:11-41.
Peters D 2000b. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.
Peters D 2009. A reinterpretation of pteroid articulation in pterosaurs. Journal of Vertebrate Paleontology 29: 1327-1330
Peters D 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.
Saller F 2016. Anatomia, paleobiologia e filogenesi di Macrocnemus bassanii Nopcsa 1930 (Reptilia, Protorosauria). Alma Mater Studiorum – Università di Bologna Dottorato di Ricerca in Scienze della Terra Ciclo XXVII 206pp.
Sanz JL and López-Martinez N 1984. The prolacertid lepidosaurian Cosesaurus aviceps Ellenberger & Villalta, a claimed ‘protoavian’ from the Middle Triassic of Spain. Géobios 17: 747-753.
Wild R 1993. A juvenile specimen of Eudimorphodon ranzii Zambelli (Reptilia, Pterosauria) from the upper Triassic (Norian) of Bergamo. Rivisita Museo Civico di Scienze Naturali “E. Caffi” Bergamo 16: 95-120.
Wild R 1978. Die Flugsaurier (Reptilia, Pterosauria) aus der Oberen Trias von Cene bei Bergamo, Italien. Bolletino della Societa Paleontologica Italiana 17(2): 176–256.

wiki/Bergamodactylus
wiki/Cosesaurus

Cartorhynchus: rebuilding the small ichthyosaur mimic

Mistakes were made here
earlier while reconstructing Cartorhynchus, the basal sauropterygian ichthyosaur-mimic. Those mistakes are corrected here (Figs. 1, 2) and already updated in earlier posts. All of these repairs further cement the relationship of Cartorhynchus to its sister, Sclerocormus  (Fig. 3) and its ancestral sister, Qianxisaurus (Fig. 4), taxa nesting near the base of the Eosauropterygia, not the Ichthyopterygia in the large reptile tree (LRT, 1401 taxa).

Figure 1. New tracing and reconstruction of the basal sauropterygian with flippers, Cartorhynchus.

Figure 1. New tracing and reconstruction of the basal sauropterygian with weak flippers, Cartorhynchus. Note the flipped maxilla, now convex ventrally. The pectoral girdle is rebuilt based on that of Qianxisaurus. See text for details. Compare pectoral elements to Qianxisaurus in figure 5.

Cartorhynchus lenticarpus (Motani et al. 2014; Early Triassic) was originally considered a strange basal ichthyosauriform and a suction feeder. Here it nests with Sclerocormus and Qianxisaurus as a basal eosauropterygian representing a new clade of ichthyosaur-mimics with a very early appearance of flipper-like limbs. Neotony played a part in the appearance of a short rostrum, large eyes, short neck, poorly ossified phalanges and small size. The supratemporal was large here, and the splenial can be seen in lateral view, though just barely. These are also results of neotony as most sauropterygians lack them. The outgroup taxon, Pachypleurosaurus, fuses the large supratemporal and squamosal

Ichthyosaurs have the following traits by convergence.
Ichthyosaurs have robust scleral rings (eyeball bones) while most eosauropterygians do not. Distinct from most eosauropterygians and like ichthyosaurs, Qianxisaurus has small supratemporals and gracile scleral rings. The splenials are not visible in the present exposure. Like Cartorhynchus, the digits of Qianxisaurus are not well developed. 

Figure 2. Cartorhynchus reconstruction in lateral and dorsal views with new lateral view skull and pectoral girdle.

Figure 2. Cartorhynchus reconstruction in lateral and dorsal views with new lateral view skull and old invalid dorsal view skull. The new pectoral girdle is in place here. The flippers seem to be relatively immobile. The tail was the main propulsive organ. Neotony created this sauropterygian with large eyes, short snout, short neck and digit-less limbs.

The premaxilla
of Cartorhynchus was tiny, ideal for nipping small food items. Small teeth were present, contra the original interpretation. The naris and orbit were quite large, distinct from all candidate sister taxa. The in situ maxilla was taphonomically flipped, so Cartorhynchus actually had a ventrally convex maxilla. The heavy ribs and flat bottom make Cartorhynchus look like a bottom feeder. The elevated dorsal neural spines suggest a dorsal fin (Fig. 2). The small scapula and coracoid suggest a weak, passive pectoral flipper. A long tail was probably present, as in its larger sister, Sclerocormus (Fig. 3). This would have been the primary propulsive organ. Note the lack of large flippers in Sclerocormus. Qianxisaurus is the last known common ancestor.

Figure 1. Large Sclerocormus and its much smaller sister, Cartorhynchus. These nest with basal sauropterygians, not ichthyosauriforms.

Figure 3. Large Sclerocormus and its much smaller sister, Cartorhynchus. These nest with basal sauropterygians, not ichthyosauriforms.

Qianxisaurus chajiangensis (Cheng et al. 2012; Fig. 4) is a Middle Triassic basal eosauropterygian based on a virtually complete articulated skeleton with all digits poorly ossified. Cheng et al. 2012 nested Qianxisaurus as derived from a sister to Wumengosaurus, a taxon that nested closer to thalattosaurs, ichthyosaurs and mesosaurs in the LRT. The Cheng et al. (2012) study had some odd nestings including Kuehneosauridae (rib gliders) a little too close to turtles and thalattosaurs. The LRT widely separated these taxa, as befitting their utterly distinct morphologies.

Figure 4. Slight changes to the temple region of Qianxisaurus shows the reappearance of the suptratemporal, which had been lost in more primitive taxa only to be reacquired here and further elaborated in Cartorhynchus.

Figure 4. Slight changes to the temple region of Qianxisaurus shows the reappearance of the suptratemporal, which had been lost in more primitive taxa only to be reacquired here and further elaborated in Cartorhynchus.

The LRT
nests Qianxisaurus between Pachypleurosaurus and LariosaurusPistosaurus nests as an outgroup in the Cheng et al. (2012) tree, but closer to Simosaurus in the LRT.

The upper temporal fenestrae of Qianxisaurus
were smaller than in Pachypleurosaurus. The supratemporal formed the posterior rim without fusion to the squamosal. In Qianxisaurus the retroarticular process of the mandible was smaller than in related taxa. The teeth of Qixiansaurus were unusual with a slightly constricted cylinder and short conical crown.

Despite the small size of the ilium
at least four sacrals were present.

The Cartorhynchus-like pectoral girdle of Qianxisaurus.
The scapula (green Fig. 5) had a slim strap-like morphology. The clavicles were broader laterally, meeting medially in an arch shape, as in Cartorhynchus (Fig. 1).

Figure 5. The Qianxisaurus pectoral girdle is ancestral to the Cartorhynchus pectoral girdle with similarly shaped elements. Compare to figure 1.

Figure 5. The Qianxisaurus pectoral girdle is ancestral to the Cartorhynchus pectoral girdle with similarly shaped elements. Compare to figure 1. Interclavicle is hidden in situ and hypothetical here based on phylogenetic bracketing. 

Mimic taxa
appear occasionally in the LRT, which, so far, has been able to lump and split mimics by testing them against all available candidate sisters. Motari et al. 2014, for all his experience and expertise in ichthyosaurs, failed to add basal eosauropterygians, like Qianxisaurus, to their taxon lists and so was not able to consider this possibility. Better not to assume things, but to let the software perform an unbiased analysis starting with a wide gamut of taxa like the LRT.

Correcting mistakes
is part of the scientific process, whether they be internal or external. 

References
Cheng YN, Wu XC, Sato T and Shan HY 2012. A new eosauropterygian (Diapsida, Sauropterygia) from the Triassic of China. Journal of Vertebrate Paleontology. 32 (6): 1335. doi:10.1080/02724634.2012.695983
Jiang D-Y, Motani R, Huang J-D, Tintori A, Hu Y-C, Rieppel O, Fraser NC, Ji C, Kelley NP, Fu W-L and Zhang R 2016. A large aberrant stem ichthyosauriform indicating early rise and demise of ichthyosauromorphs in the wake of the end-Permian extinction. Nature Scientific Reports online here.
Motani R et al. 2014. A basal ichthyosauriform with a short snout from the Lower Triassic of China. Nature doi:10.1038/nature13866

wiki/Qianxisaurus
wiki/Cartorhynchus
wiki/Sclerocormus

 

Libonectes enters the LRT

After applying colors to
the bones in a photograph of the skull of Libonectes (Fig. 1, Turonian, early Late Cretaceous, Welles 1949, originally Elasmosaurus morgani), the Carpenter 1997 drawing was added to gauge similarities and difference. A transparent GIF makes this easy. Comparisons to the earlier (Late Triassic) Yunguisaurus and Thalassiodracon are instructional. These taxa also rotate the orbits anteriorly, providing binocular vision. The pterygoid (dark green) pops out slightly behind the jugal.

Figure 1. The skull of Libonectes. Freehand drawing from Carpenter xxxx. DGS colors added here. Some parts of the original fossil may be restored.

Figure 1. The skull of Libonectes. Freehand drawing from Carpenter 1997. DGS colors added here. Some parts of the original fossil may be restored. The fossil may be more fully prepared than this now. Note the slight differences between the fossil and drawing. The orbits appear to permit binocular vision.

Libonectes morgani, (Welles 1949, Elasmosaurus morgani, Carpenter 1997) an elasmosaur of the Turonian, early Late Cretaceous. In the large reptile tree (LRT, 1399 taxa) this skull nests with the skull-less Albertonectes (Fig. 2) and Plesiosaurus (Fig. 3) at first with no resolution owing to the lack of common traits between the skull-only and skull-less taxa.

Figure 3. Plesiosaurus skull in several views alongside the pectoral girdle.

Figure 2. Plesiosaurus skull in several views representing two specimens alongside the pectoral girdle. Data comes only from this drawing, not the fossil itself, which I have not yet seen.

Later the post-crania of Libonectes is added
and the two elasmosaurs now nest together sharing fore limbs slightly longer than hind limbs (Fig. 3) among several other less obvious traits. Neck length, much longer with more vertebrae than in Plesiosaurus, scores the same, “Presacral vertebrae, 31 or more” in the LRT.

Figure 1. Libonectes flippers. 2nd frame shows PILs. Terrestrial tetrapods flex and extend along continuous PILs. The in vivo misalignment of phalanges in Libonectes largely prevents flexion and extension, creating a large stiff flipper at misaligned PILs. Those that are more proximal are continuous, permitting a limited amount of flexion and extension.

Figure 3. Libonectes flippers. 2nd frame shows PILs. Terrestrial tetrapods flex and extend along continuous PILs. The in vivo misalignment of phalanges in Libonectes largely prevents flexion and extension, creating a large stiff flipper at misaligned PILs. Those that are more proximal are continuous, permitting a limited amount of flexion and extension.

Sachs and Kears 2017
bring us images and descriptions of the post-crania of Libonectes, a Late Cretaceous elasmosaur, one of the sauropterygian plesiosaurs, similar in most respects to the other tested elasmosaur, Albertonectes, which we looked at earlier here.

Distinct from terrestrial tetrapods
that flex and extend their phalanges along continuous PILs, the in vivo misalignment of phalanges in Libonectes largely prevents flexion and extension, creating a stiffer flipper at the misaligned PILs. Note, those that are more proximal are continuous, permitting more flexion and extension.

PILs were first documented
in Peters 2000. Many taxa may be distinguished by their fore and hind PIL patterns as also shown for pterosaurs in Peters 2011.

It is worth noting (and scoring)
that the forelimbs are slightly larger than the hind limbs in elasmosaurs, distinct from other sauropterygians, convergent with many ichthyosaurs, sea turtles and perhaps other taxa I am overlooking presently (overlooking some birds and all bats and pterosaurs for the moment, because they fly).

Figure 5. Elasmosaurid origins. The long neck preceded the flippers in this clade of vertical feeders.

Figure 4. Elasmosaurid origins. The long neck preceded the flippers in this clade of vertical feeders.

We looked at hypothetical elasmosaur swimming techniques
a few months ago here.

References
Carpenter K 1999. Revision of North American elasmosaurs from the Cretaceous of the western interior. Paludicola, 2(2): 148-173.
Sachs S and Kear BP 2017. Redescription of the elasmosaurid plesiosaurian Libonectes atlasense from the Upper Cretaceous of Morocco. Cretaceous Research 74:205–222.
Welles SP 1949. A new elasmosaur from the Eagle Ford Shale of Texas. Fondren
Science Series, Southern Methodist University 1: 1-28.

wiki/Albertonectes
wiki/Libonectes

Looking for a vestigial toe 5 on Jeholosaurus

Jeholosaurus is a small Early Cretaceous sister
to the Late Jurassic Chilesaurus and Late Triassic Daemonosaurus. All three nest as basalmost Ornithischia in the large reptile tree (LRT, 1399 taxa).

Phylogenetic bracketing indicates
a likely pedal digit 5 with a few phalanges should be found on all three taxa. Prior studies failed to reveal it. Current data does not include the pes for Daemonosaurus, nor show the ventral aspect of Chilesaurus, but Jeholosaurus does present the view we’re looking for (Fig. 1). I failed to notice pedal 5 before. I think others have overlooked it as well. Here it is:

Figure 1. Jeholosaurus pes in ventral aspect. DGS colors identify parts of pedal digit 5 disarticulated and broken on the sole of the foot and reconstructed at right.

Figure 1. Jeholosaurus pes in ventral aspect. DGS colors identify parts of pedal digit 5 disarticulated and broken on the sole of the foot and reconstructed at right. This observation is awaiting confirmation or refutation. Phylogenetic bracketing indicates this foot had a pedal digit 5 in vivo.

Finding pedal digit 5 on Jeholosaurus
was made a bit more difficult due to the vestige nature of the digit and its crushed and broken pieces, disarticulated from its traditional alignment lateral to pedal digit 4. This observation based on this photo awaits confirmation or refutation.


References
Han F-L, Barrett PM, Butler RJ and Xu X 2012. Postcranial anatomy of Jeholosaurus shangyuanensis (Dinosauria, Ornithischia) from the Lower Cretaceous Yixian Formation of China. Journal of Vertebrate Paleontology 32 (6): 1370–1395.
Xu X, Wang and You 2000. A primitive ornithopod from the Early Cretaceous Yixian Formation of Liaoning. Vertebrata PalAsiatica 38(4:)318-325.

wiki/Jeholosaurus
wiki/Daemonosaurus

 

 

Outdated paleontology textbooks

Following in the wake of the fading paleo textbook I grew up with,
Vertebrate Paleontology (Carroll 1988), comes more recent editions from Professor Michael Benton (3rd edition 2005; 4th edition 2014, Fig. 1).

Figure 1. Vertebrate Paleontology by M. Benton.

Figure 1. Vertebrate Paleontology by M. Benton.

Prior reviews:
“The book is a main textbook for vertebrate palaeontology and aimed at students and anyone with an interest in the evolution of vertebrates. It meets its five aims and is excellent value.” 
(Proceedings of the Open University Geological Society, 1 April 2015)

From the Amazon.com website:
“This new edition reflects the international scope of vertebrate palaeontology, with a special focus on exciting new finds from China. A key aim is to explain the science. Gone are the days of guesswork. Young researchers use impressive new numerical and imaging methods to explore the tree of life, macroevolution, global change, and functional morphology.

“The fourth edition is completely revised. The cladistic framework is strengthened, and new functional and developmental spreads are added. Study aids include: key questions, research to be done, and recommendations of further reading and web sites.

“The book is designed for palaeontology courses in biology and geology departments. It is also aimed at enthusiasts who want to experience the flavour of how the research is done. The book is strongly phylogenetic, and this makes it a source of current data on vertebrate evolution.”

A review from the perspective of the large reptile tree
Unfortunately this volume invalidates itself by taxon exclusion at many nodes. Readers are better served at ReptileEvolution.com where taxa are included and tested, not just reported on.

Dr. Benton has been caught excluding taxa
in the past (e.g. Hone and Benton 2007, 2009Yang et al. 2018) to support his own outdated and invalidated hypotheses (like Scleromochlus, the bipedal croc with tiny hands as a sister to Bergamodactylus, the basal pterosaur with giant hands). His textbook presents several falsehoods about pterosaurs (e.g. open ventral pelvis, all were quadrupedal, origin from archosaurs). The first dichotomy splitting the Reptilia into Lepidosauromorpha and Archosauromorpha is not presented, leading to many mix-ups in derived taxa. Lacking is a wide gamut specimen-based phylogenetic analysis, like the large reptile tree, a modern requirement for every textbook on this subject in the present cladistic era. Rather, a number of smaller, more focused previously published studies are presented without review or criticism.

Finally,
because the Benton volume is a physical book, it cannot keep up with the weekly and daily additions of online competitors, like www.ReptileEvolution.com is able to do. The Benton book, and all such textbooks, start to become outdated the moment the authors submit their final drafts to the publishers, weeks or months before their publication dates. It’s just the nature of publishing. It cannot be avoided due to this time lag.

Popular books make similar mistakes
Naish and Barrett 2016 wrote a dinosaur book, “Informed by the latest scientific research.” Sadly, no. This book is a journalistic compendium of prior studies, many of which were invalidated by taxon exclusion. As in most traditional studies, bipedal crocs are ignored in their cladograms dealing with the origin of dinos. These authors also considered tiny bipedal Scleromochlus ancestral to pterosaurs + Dinosauromorpha (p. 34), following Benton 1999. This hypothesis of relationships was invalidated by Peters 2000 who simply added taxa ignored by 4 prior authors, including Benton 1999. We can also be disappointed that these PhD authors bought into the bogus Yi qi styliform reconstruction as a bat-winged bird amalgam without either a critical analysis or a second thought of this one-of-a-kind mistake. The authors also supported the debunked origin of birds from theropods of descending size (pp. 184–185). Authors and editors should have checked for logic errors like the following from Naish and Barrett: “The fact that a microraptor specimen preserves a fish in its belly, indicates that they were also spending time on the ground.”

Just let that sink in if you don’t get it right away.

Parker 2015
reports on traditional mishandlings of the evolution of reptiles considered and criticized here at ReptileEvolution.com and PterosaurHeresies. As is typical in traditional paleontology, too often sister taxa in Parker 2015 do not document a gradual accumulation of derived traits. For instance the first dichotomy in the Parker topology splits Synapsids from Sauropsids. So no amphibian-like reptiles are recognized. The next dichotomy splits Eureptilia from Anapsida / Parareptilia. So pareiasaurs nest with mesosaurs. Parker considers the origin of ichthyosaurs and turtles, “uncertain.” A wide gamut cladogram testing all possibilities has no such problem Parker splits the invalid clade Sauria into Lepidosauromorpha and Archosauromorpha, then splits Sauropterygia and Lepidosauria, then lumps Pterosauria and Dinosauria together in the invalid clade Avemetatarsalia / Ornithodira. And with Avemetatarsalia we once again return to Benton 1999, which keeps surviving like a zombie.

As others have noted,
the present day is a ‘Golden Age’ in paleontology where discoveries are being posted weekly if not daily. Paper textbooks just cannot keep up with the latest hypotheses of relationships when compared to online studies and critiques that can pop up within hours of academic publication.

Benton would not have written editions 1 and 2
unless Carroll 1988 had become obsolete. Benton would not have written editions 3 and 4 if he didn’t think the earlier editions were failing to keep with our understanding of paleontology. Given the time it takes to produce, publish and distribute giant textbooks, It may be time for textbooks to go extinct and evolve into current online information.

References
Benton MJ 2005. Vertebrate Paleontology 3rd Edition PDF online Wiley-Blackwell 455 pp.
Benton MJ 2014. Vertebrate Paleontology 4th Edition Wiley-Blackwell 480 pp.
Carroll RL 1988. Vertebrate Paleontology and Evolution. WH Freeman and Co. New York.
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.
Naish D and Barrett P 2016. Dinosaurs. How they lived and evolved. Smithsonian Press.  online here.
Parker S (general editor) 2015. Evolution. The whole story. Firefly Books 576 pp.
Peters D 2000. A redescription of four prolacertiform genera and implications for pterosaur phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106: 293-336

 

Deinogalerix: not a giant extinct hedgehog, but close!

Rather,
Deinogalerix (Fig. 1, 2) is a giant moonrat, (Fig. 3) according to its nesting in the large reptile tree (LRT, 1399 taxa)

Figure 1. Skull of Deinogalerix with bones colored in DGS overlay.

Figure 1. Skull of Deinogalerix with bones colored in DGS overlay. Note the separation of the prefrontal and lacrimal along with the large size of the premolars relative to the small molars.

Deinogalerix koenigswaldi  (Freudenthal 1972; Villiera et al. 2013; Late Miocene 10-5mya; skull length 20cm, snout-vent length 60cm) is the extinct giant moon rat (not hedgehog), restricted to a Mediterranean island, now part of a peninsula. Giant premolars and tiny molars make the dentition unusual. Seven species have been identified.

Figure 2. Deinogalerix skeleton.

Figure 2. Deinogalerix skeleton. Snout to vent length = 60cm.

Echinosorex gymnura (Blainville 1838; length to vent up to 40cm, tail up to 30cm, Fig. 3) is the extant moonrat, or gymnure, an omnivore that looks like an opossum or rat. Here it nests with Pholidocercus, a Messel pit armadillo-mimic we looked at earlier here. Distinct from most Glires, the canines are large.

Figure 3. Echinosorex, the extant moonrat, looks like an opossum, but nests with Deinogalerix in the large reptile tree.

Figure 3. Echinosorex, the extant moonrat, looks like an opossum, but nests with Deinogalerix in the large reptile tree.

References
Freudenthal M 1972. Deinogalerix koenigswaldi nov. gen., nov. spec., a giant insectivore from the Neogene of Italy. Scripta Geologica. 14: 1–19.
Villiera B, Van Den Hoek Ostendeb L, De Vosb J and Paviaa M 2013. New discoveries on the giant hedgehog Deinogalerix from the Miocene of Gargano (Apulia, Italy). Geobios. 46 (1–2): 63–75.

.

 

Teraterpeton: more post-crania

Pritchard and Sues 2019
bring us additional post-cranial data on Teraterpeton (Fig. 1, Sues 2003), the long-snouted sister to Trilophosaurus with an atypical antorbital fenestra and displaced naris.

Figure 1. Teraterpeton with new elements added. Toes are largely unknown, but added here based on proximal phalanges.

Figure 1. Teraterpeton with new elements added. Toes are largely unknown, but added here based on proximal phalanges. None of these elements come as a surprise, based on phylogenetic bracketing in the LRT. Note the lepidosaur-like hind limbs, because this IS a lepidosaur.

Teraterpeton hrynewichorum (Sues 2003, Pritchard and Sues 2019) Late Triassic, ~215 mya, was described as euryapsid (lacking a lateral temporal fenestra) and possibly related to the rhynchocephalian, Trilophosaurus on that basis. Here Teraterpeton is a sister to Trllophosaurus, but with a stretched out rostrum, an antorbital fenestra and fewer teeth, still characteristically narrower at the root line. Teraterpeton also nests between Sapheosaurus and Mesosuchus. at the junction between the primitive sphenodontids and the advanced rhynchosaurs (see the LRT), all within the Lepidosauria. The manual unguals are robust with disparate sizes. The large acetabulum was open posteriorly and taller than the rest of the ilium. The metatarsals overlapped considerably. The asymmetry of the metatarsals is typical of sprawling taxa, like lizards.

Figure 2. Cladogram from Pritchard and Sues 2019 showing the nesting of Teraterpeton with Trilophosaurus. The yellow taxa are lepidosauromorphs and the green taxa are archosauromorphs in the LRT. Taxon exclusion folds them together like a deck of cards.

Figure 2. Cladogram from Pritchard and Sues 2019 showing the nesting of Teraterpeton with Trilophosaurus. The yellow taxa are lepidosauromorphs and the green taxa are archosauromorphs in the LRT. Taxon exclusion folds them together like a deck of cards.

The Pritchard and Sues (P+S) Teraterpeton cladogram
(Fig. 2) shuffles lepidosauromorphs (yellow) and archosaurmorphs (green) together like a deck of cards. Unfortunately the authors were following old traditional cladograms that wrongly considered Diapsida monophyletic. The large reptile tree (LRT, 1395 taxa) separates lepidosauromorphs from archosauromorphs at the first reptile dichotomy, a factor not recognized by the authors. Taxon exclusion is a problem here.

Where do we agree?

  1. Coelurosauravus and kin nest with drepanosaurs.
  2. Teraterpeton is close to Trilophosaurus, Shringisaurus and Azendohsaurus
  3. Lepidosaurs, like Huehuecuetzpalli, nest close to Rhynchocephalians
  4. Tritosaurs, like Macrocnemus, nest with Tanystropheus

Where do we disagree?

  1. The glider Coelurosauravus should nest with the gliding kuehneosaurs, not close to the aquatic Claudiosaurus.
  2. but not with unrelated basal diapsids, like Petrolacosaurus and Orovenator, which nest in the Archosauromorpha.
  3. All the protorosaurs (Prolacerta, Pamelaria, Protorosaurus, Boreopricea, Ozimek, should nest together.

Without an understanding
of the basal Lepidosauromorpha/Archosauromorpha dichotomy following the basalmost amniote, Silvanerpeton in the Viséan, taxon exclusion blurs the differences between archosauromorph-like lepidosaurs and lepidosaur-like protorosaurs, convergent with one another.

Convergence is revealed by the LRT
not by the Pritchard and Sues cladogram that suffers from taxon exclusion. Add taxa to recover the basal split between the new Archosauromorpha and the new Lepidosauromorpha.

References
Pritchard AC and Sues H-D 2019. Postcranial remains of Teraterpeton hrynewichorum
(Reptilia: Archosauromorpha) and the mosaic evolution of the saurian postcranial skeleton. Journal of Systematic Palaeontology, DOI: 10.1080/14772019.2018.1551249
Sues H-D 2003. An unusual new archosauromorph reptile from the Upper Triassic Wolfville Formation of Nova Scotia. Canadian. Journal of Earth Science 40(4): 635-649.

 

Eofringillirostrum: a tiny Eocene crake, not a finch

Ksepka, Grande and Mayr 2019
describe two Early Eocene congeneric bird species. Eofringillirostrum parvulum (Fig. 1) is from Germany, 47mya. Eofringillirostrum boudreauxi from Wyoming, 52mya.

Figure 1. Eofringillirostrum in situ at full scale at 72 dpi and closeups of the skull in situ with DGS tracing and reconstructed. Note the slender vomer (purple).

Figure 1. Eofringillirostrum in situ at full scale at 72 dpi and closeups of the skull in situ with DGS tracing and reconstructed. Note the slender vomer (purple) and the added detail gleaned with DGS compared to the original tracing in figure 2.

Eofringillirostrum boudreauxi, E. parvulum (Ksepka, Grande and Mayr 2019; IRSNB Av 128a+bFMNH PA 793; early Eocene; < 10cm long with feathers) was originally considered a finch and a relative of Pumiliornis, a wren-sized Middle Eocene spoonbill. Here Eofringillirostrum nests as a phylogenetically miniaturized corn crake (below). The rail, Crex, is ancestral to chickens, sparrows, moas and parrots, so Eofringillirostrum probably had a Cretaceous origin. A distinctly long fourth toe  was considered capable of being reversed, but no sister taxa with a similar long toe ever reverse it for perching until, many nodes later, parrots appear.

Figure 1. Much enlarged Eofringillirostrum with original tracing and DGS colors. The crest of the sternum, originally overlooked, is just barely ossified here.

Figure 1. Much enlarged Eofringillirostrum with original tracing and DGS colors. The crest of the sternum, originally overlooked, is just barely ossified here.

Corn crake are not ‘perching birds’. 
As we learned earlier, taxa formerly considered members of Passeriformes are a much smaller list in the LRT. Birds capable of perching arise in several clades by convergence.

The corn crake is omnivorous but mainly feeds on invertebrates, the occasional small frog or mammal, and plant material including grass seed and cereal grain. It is not a perching bird, but prefers grasslands.

Figure 4. The extant corn crake (Crex) is a living relative of the giant elephant bird.

Figure 4. The extant corn crake (Crex) is a living relative of the tiny Eocene Eofringillirostrum.

According to the LRT,
Eofringillirostrum is not a finch, not a seed eater and not a ‘perching bird’ (in the classic sense, but likely evolved perching by convergence) according to phylogenetic analysis and phylogenetic bracketing.)

Figure 5. Skull of Crex most closely resembles that of the new Crex sister, Eofingillirostrum.

Figure 5. Skull of Crex most closely resembles that of the new Crex sister, Eofingillirostrum.

References
Ksepka DT, Grande L and Mayr G 2019. Oldest Finch-Beaked Birds Reveal Parallel Ecological Radiation in the Earliest Evolution of Passerines. Current Biology 29, 1–7.

sciencedaily.com