Enigmatic Jamoytius enters the LRT

Sansom et al. 2010 studied and discussed
Jamoytius kerwoodi (White 1946; Early Silurian; Fig. 1) an early eel-like taxon originally considered to be the most primitive known vertebrate, then a sister to lampreys, then a sister to Euphanerops (the subject of yesterday’s post). Turns out, it is none of these.

Sansom et al write:
“The study of the anatomy of problematic organisms can be aided by the use of a methodology designed to separate topological and morphological reconstruction from anatomical interpretation and to gather as much information as possible about the preserved features through taphonomic analyses.”

Unfortunately the authors did not trace the skull bones (Fig. 1) and those of several related taxa (Figs. 3, 4) and so missed the ability to score Jamoytius more completely and accurately.

“Interpretations of paired fins remain equivocal. Analyses of the phylogenetic affinity of Jamoytius identify a sister taxon relationship with Euphanerops. This clade, the Jamoytiiformes, is a primitive group of stem-gnathostomes and does not form a clade with the Anaspida.”

By contrast, the large reptile tree (LRT, 1718+ taxa, subset Fig. 2) nests Jamoytius not with lampreys, nor with Euphanerops, but between Birkenia (Fig. 3) and Thelodus (Fig. 4), taxa ignored by Sansom et al.

Figure 1. Jamoytius photo and diagram from Sansom et al. 2020. Colors and new labels added here.

Figure 1. Jamoytius photo and diagram from Sansom et al. 2020. Colors and new labels added here. Note the lack of skull bone tracings on the diagram. It looks like each gill opening has a little opercular flap. Note the new identification for the left eye. The ‘notochord’ is here a dorsal ridge, a precursor to dorsal armor.

Jamotius kerwoodi (White 1946, Sansom et al. 2010; Early Silurian; 10+cm in length) shares a tiny circular mouth and naris at the tip of its short snout with closely related taxa along with a similar set of skull bones, plus a dorsal ridge!

Figure 2. Subset of the LRT focusing on basal chordates and Jamoytius.

Figure 2. Subset of the LRT focusing on basal chordates and Jamoytius.

 With a small circular oral cavity,
Jamoytius and its sisters could not have been open sea predators, or blood suckers, but likely scoured sea muds and lake sands for tiny buried prey, like young lancelets and This extant sturgeons. Sturgeons (Fig. 4) feed on a spectrum of small benthic prey. Larger  sturgeons are known to suck in larger prey, like salmon, into their toothless, nearly jawless oral cavity.

BTW,
these taxa are all buried deep in the human lineage. So, say ‘hello’ to your ancestors.

Figure 3. Birkenia skull for comparison to Jamoytius.

Figure 3. Birkenia skull for comparison to Jamoytius.

Paleontologists of all stripes are fond of saying,
‘first-hand examination of the fossil is essential’. Sansom et al. had several fossils to look at firsthand and did not trace skull bones (Fig. 1). As I’ve been saying for nine years, the computer monitor and a digitally scanned photo can be superior to a binocular microscope because the monitor can trace elements in color, thereby reducing the apparent chaos into discrete segregated units. That opens up a whole new world of data that can be used to confidently nest enigmatic taxa, like Jamoytius (Fig. 2).

Figure 7. Top to bottom: Thelodus a soft jawless fish with a ventral oral opening and gill slits, perhaps a hint of diamond-shaped armor laterally. Hemicyclaspis, adds extensive armor. Euphaneropsps, a late survivor of an Ordovician radiation basal to sturgeons. Acipenser, a sturgeon with a protrusible tube for a mouth and reduced armor. Chondrosteus, a fish with jaws, but no marginal teeth.

Figure 4. Top to bottom: Thelodus a soft jawless fish with a ventral oral opening and gill slits, perhaps a hint of diamond-shaped armor laterally. Hemicyclaspis, adds extensive armor. Euphaneropsps, a late survivor of an Ordovician radiation basal to sturgeons. Acipenser, a sturgeon with a protrusible tube for a mouth and reduced armor. Chondrosteus, a fish with jaws, but no marginal teeth.

Taxon exclusion, once again. 
Sansom et al. did not mention, trace and test either Birkenia (Fig. 3) or Thelodus (Fig. 4). So taxon exclusion is also an issue resolved here by the LRT using character traits originally designed for reptiles and still working in basal chordates. It’s that simple. Just add taxa and enigmas get confidently nested.


References
Sansom RS, Freedman K, Gabbott SE, Aldridge RJ and Purnell MA 2010. Taphonomy and affinity of an enigmatic Silurian vertebrate, Jamoytius kerwoodi White. Palaentology 53(6):1393–1409.
White EI 1946. Jamoytius kerwoodi, a new chordatefrom the Silurian of Lanarkshire. Geological Magazine, 83, 89–97.

wiki/Jamoytius

Euphanerops: basal to sturgeons with tiny new pelvic fins

Janvier and Arsenault 2007 took another look at
Euphanerops longaevus (Woodward 1900; Late Devonian, Figs. 1, 2) comparing it uncertainly to living lampreys and extinct jawless, finless fish. They report, “The anatomy of Euphanerops longaevus is reconstructed here on the basis of 17 specimens, 14 of which were hitherto undescribed. Practically all the mineralized elements that can be observed in the largest individuals of E. longevous display the same structure, which strikingly recalls that of lamprey cartilage, despite the uncertainty as to the origin of its mineralization.”

Elongated and confluent paired fins
“The new material of E. longaevus described here provides strong support for the presence of ventrolateral, ribbon-shaped, paired fins armed with numerous parallel radials. These fins extend from the anus to the anterior part of the branchial apparatus anteriorly, and are the first instance of paired fins with radials, whose anteroposterior extension largely overlaps that of the branchial apparatus in a vertebrate.”

Mostly true, but let’s not forget in manta rays and guitarfish, skates and rays, paired pectoral fins indeed do overlap the branchial apparatus (= gill basket), IF that is happening in Euphanerops (see below).

From the abstract
“Owing to the uncertainty as to the biogenic or diagenetic nature of the anatomical features described in E. longevous, no character analysis is proposed. Only a few possible homologies are uniquely shared by euphaneropids and either lampreys or anaspids, or both.”

Phylogenetically, the authors note:
“Euphanerops longaevus has been referred to as an anaspid, chiefly because of its distinctive hypocercal tail and anal fin. However, since it apparently has no mineralized dermal skeleton, E. longaevus lacks evidence for the tri-radiate postbranchial spine, which Forey (1984) proposed as the defining character of the Anaspida. Consequently, it is now often treated in recent phylogenetic analyses as a separate terminal taxon, alongside other scale-less (or “naked”) jawless vertebrate taxa also once regarded as anaspids, namely Endeiolepis and Jamoytius.”

Figure 1. Several basal chordates: Branchiostoma, Euphanerops, Jamoytius and Birkenia. The middle image of Euphanerops is the tracing. The others are freehand interpretations not supported here.

Figure 1. Several basal chordates: Branchiostoma, Euphanerops, Jamoytius and Birkenia. The middle image of Euphanerops is the tracing. The others are freehand interpretations from Janvier and Arsenault 2007.

Here 
(Fig. 2) individual skull bones and tiny overlooked pectoral and pelvic fins are identified. Adding a missing (unossified?) rostrum (= nasal) restores the original profile. In the large reptile tree (LRT, 1717+ taxa) Euphanerops nests basal to sturgeons, like Pseudoscaphirhynchus (FIg. 3), a clade not mentioned by Janvier and Arsenault 2007. A previously enigmatic element in front of the mouth is here identified as a pair of barbels, as in sturgeons. The tiny dorsal spines of Euphanerops are also found as larger dorsal armor in Birkenia, osteostracans and sturgeons.

Figure 2. Euphanerops skull region showing tetrapod homolog bones and displace fin. See Birkenia for closer homologs. Image from Janvier and Arsenault 2007. Colors added here.

Figure 2. Euphanerops skull region showing tetrapod homolog bones and displace fin. See Birkenia for closer homologs. Image from Janvier and Arsenault 2007. Colors added here.

According to Wikipedia
Euphaneropidae have, “greatly elongated branchial apparatus which covers most of the length of the body.”

Here that area is identified as a typical subdivided and flattened ventral surface, as in Birkenia, sturgeons and osteostracans.

Figure 1. Skull of Pseudoscaphorhynchus. Note the mouth is created by the lacrimal and surangular, not the maxilla and dentary, which are tooth-bearing bones in more derived fish.

Figure 3. Skull of Pseudoscaphorhynchus. Note the mouth is created by the lacrimal and surangular, not the maxilla and dentary, which are tooth-bearing bones in more derived fish.

The hypocercal tail of Euphanerops
has heterocercal elements and this taxon nests between taxa with a heterocercal tail. With an Ordovician genesis, Late Devonian Euphanerops likely developed a dipping tail and larger propulsive dorsal fin secondarily, as a reversal. An ancestor, Birkenia, has a similar dipping tail.

Figure 4. Euphanerops caudal fin with elements re-identified.

Figure 4. Euphanerops caudal fin with elements re-identified.

Small enigmatic squares of rod-like elements near the cloaca
are here identified as primitive pelvic fins or vestiges of the same. More primitive taxa do not have pelvic fins. More derived taxa do.

Figure 3. Euphanerops with elements here identified as tiny pectoral fins just anterior to the cloaca.

Figure 5. Euphanerops with elements here identified as tiny pectoral fins just anterior to the cloaca and posterior to the ventral armor. Images from Janvier and Arsenault 2007.

Primitive pectoral fins
are known in ancestral and descendant taxa, so Euphanerops should have them, too. Here (Fig. 6) they are identified as vestiges.

Figure x. Euphanerops plate and counter plate with colors added identifying elements.

Figure 6. Euphanerops plate and counter plate with colors added identifying elements.

Traditionally sturgeons have not been tested with osteostracans
(Fig. 7) and other jawless fish. The LRT tests a wide gamut of competing candidates and nests sturgeons prior to the advent of jaws and teeth in vertebrates, close to osteostracans and Euphanerops. Do not let one or two traits, like a dipping (hypocercal) tail, steer you off course in your wide-gamut analysis.

Figure 7. Top to bottom: Thelodus a soft jawless fish with a ventral oral opening and gill slits, perhaps a hint of diamond-shaped armor laterally. Hemicyclaspis, adds extensive armor. Euphaneropsps, a late survivor of an Ordovician radiation basal to sturgeons. Acipenser, a sturgeon with a protrusible tube for a mouth and reduced armor. Chondrosteus, a fish with jaws, but no marginal teeth.

Figure 7. Top to bottom: Thelodus a soft jawless fish with a ventral oral opening and gill slits, perhaps a hint of diamond-shaped armor laterally. Hemicyclaspis, adds extensive armor. Euphaneropsps, a late survivor of an Ordovician radiation basal to sturgeons. Acipenser, a sturgeon with a protrusible tube for a mouth and reduced armor. Chondrosteus, a fish with jaws, but no marginal teeth.

The ‘paired fin ridges’ observed by Janvier and Arsenault
may be ray-like ossifications that gathered to produce the ventrolateral armor on sturgeons (Fig. 7) or were vestiges thereof. Additionally, that’s where basal chordate gonads are located.

A set of lamprey-like gill openings appear near the skull
of Euphanerops. This appears to be a retention of or reversal back to similar multiple openings seen in Birkenia (Fig. 1). Again, don’t judge a taxon by one or two traits. Test them all against a wide gamut of taxa, like the LRT. We may be seeing what happens a the transition from multiple gill openings to a sturgeon-like operculum here.


References
Janvier P, Desbiens S, Willett JA and Arsenault 2006. Lamprey-like gills in a gnathostome related Devonian jawless vertebrate. Nature 440:1183–1185.
Janvier P and Arsenault M 2007. The anatomy of Euphanerops longaevus Woodward, 1900, an anaspid-like jawless vertebrate from the Upper Devonian of Miguasha, Quebec, Canada. Geodiversitas 29 (1) : 143-216.
Woodward AS 1900. On a new ostracoderm fish (Euphanerops longaevus) from the Upper Devonian of Scaumenac Bay, Quebec, Canada. Magazine of Natural History ser. 7, 5: 416-419.

wiki/Euphaneropidae

Platysomus sheds new light on placoderms

Short one today.
One more fish enters the LRT. Some changes (like a prefrontal) are added to previously nested taxa.

Adding the Carboniferous fish,
Platysomus (Fig. 1) , to the large reptile tree (LRT, 1713+ taxa; Fig. 2) to no one’s surprise nests it with Cheirodus (= Chirodus, Amphicentrum; Fig. 1), a less stretched-out version.

The heresy is
these two taxa nest with catfish and placoderms (Fig. 2) when allowed to do so by taxon inclusion, as we’ve seen previously. Placoderms evolve from ordinary fish.

Figure 1. Platysomus and Cheirodus are both platysomids, related to catfish and placoderms. All these taxa lack maxillae.

Figure 1. Platysomus and Cheirodus are both platysomids, related to catfish and placoderms. All these taxa lack maxillae. Note the relabeling on Platysomus.

None of these taxa
have a maxilla and they share a long list of other synapomorphic traits.

Figure 3. Subset of the LRT focusing on fish and updated here.

Figure 3. Subset of the LRT focusing on fish and updated here. Catfish and placoderms are located in the center of this diagram.

Another traditional platysomid, 
Eurynotus (Fig. 4), is even closer to the placoderms Coccosteus (open sea predators) and Entelognathus (bottom dwellers).

Figure 2. Eurynotus is another platysomid, basal to the placoderms Coccosteus and Entelognathus.

Figure 2. Eurynotus is another platysomid, basal to the placoderms Coccosteus and Entelognathus. Sharp-eyed readers will notice several skull identity changes in placoderms based on what was learned from this taxon.

Platysomus parvulus (Agassiz 1843, Carboniferous to Permian; 18cm long) is a taller, more disc-like fish related to Cheirodus. Note the reduction of the mandible. Considered a plankton eater.

Apologies for the bone ID changes.
I’m learning as I go and revising the naming system so homologies with tetrapods can be more readily understood. Someone had to do it. Why wait until 2021 or thereafter?


References
Agassiz L 1833, 1837 in Agassiz L 1833-1843. Recherches sur les Poissons fossiles-I, I, III, Neuchatel, pp 1420.

 

Sookias et al. 2020: Euparkeria updated, cladogram outdated

Cutting to the chase: 
No one has studied and published on Euparkeria (Figs. 3-6) more than Roland Sookias and his colleagues (Sookias et al.  2014, Sookias 2016, Sookias et al. 2020). Unfortunately taxon exclusion mars all of his work (Figs. 1, 2), including his latest, otherwise terrific paper presenting close-up and µCT scans from the ten specimens found in a single locality, all attributed to Euparkeria. This paper is so rich in data, but so poor and misleading in systematics.

From the abstract:
“The archosauriform Euparkeria capensis from the Middle Triassic (Anisian) of South Africa has been of great interest since its initial description in 1913, because its anatomy shed light on the origins and early evolution of crown Archosauria and potentially approached that of the archosaur common ancestor.”

In the large reptile tree (LRT, 1714+ taxa, subset Fig. 1) Euparkeria nests far from Archosauria (= the last common ancestor of birds + crocs). Instead Euparkeria nests at the base of the Euarchosauriformes (= all archosauriforms closer to Euparkeria than to Proterosuchus and the pararchosauriforms, Fig. 1). These clades were separated in 2012 here, and that split has remained steady despite many additional taxa.

Figure 1. Subset of the LRT focusing on Archosauriformes. Clade colors match figure 2 overlay.

Figure 1. Subset of the LRT focusing on Archosauriformes. Clade colors match figure 2 overlay.

Phylogenetic analysis
Sookias et al. 2020 worked from a dataset in Sookias 2016. Sookias 2016 was built on the invalidated Nesbitt 2011 and Sookias et al. 2014. The Sookias et al. 2020 results are typical whenever taxon exclusion shuffles the clades, mixing unrelated taxa together. Clades nest where they do in Sookias 2020 by default. That’s how you get crocs and phytosaurs nesting together and euparkeriids arising from erythrosuchids (Fig. 2), rather that the other way around, as in the LRT (Fig. 1). We’re also wary of any cladogram that includes suprageneric taxa.

Figure 2. Sookias et al. 2020 cladogram lacks enough taxa compared to the LRT (Fig. 2) and so shuffles clades here. Here crocs nest within 'Other Pseudosuchia' and pterosaurs nest within Ornithodira, two clades invalidated by the LRT by adding taxa. Promoting this outdated myth of interrelationships in 2020 is not professional.

Figure 2. Sookias et al. 2020 cladogram lacks enough taxa compared to the LRT (Fig. 2) and so shuffles clades here. Here crocs nest within ‘Other Pseudosuchia’ and pterosaurs nest within Ornithodira, two clades invalidated by the LRT by adding taxa. Promoting this outdated myth of interrelationships in 2020 is not professional. Dongusuchus and Dorosuchus are know from bits and pieces of the post-crania.

Euparkeria has been studied previously,
but never so completely as in Sookias et al. 2020. As in Ewer (1965, Fig. 3) Sookias et al. present a freehand diagram chimaera skull (Figs. 4, 5) that combines data from several specimens they consider to be conspecific.

Figure x. Previous views of Euparkeria.

Figure 3. Previous views of Euparkeria.

Comparing a photo of the SAM 5867 specimen
to the Sookias et al. diagram may be instructive. Did they get all the details right?

Figure x. How does the skull of the 5867 specimen of Euparkeria compare to the diagram? Here they are to the same scale.

Figure 4. How does the skull of the 5867 specimen of Euparkeria compare to the diagram? Here they are to the same scale. You decide on the details.

Several color photos were included in Sookias et al. 2020,
so it is surprising that their diagram lacks colors (Fig. 5 left column). When colors are added, the bones lump and separate as well as the LRT lumps and separates taxa.

Figure x. Diagram from Sookias 2020 at left. Rearranged and colored at right for ease of viewing.

Figure 5. Diagram from Sookias et al.  2020 at left. Rearranged and colored at right for ease of viewing.

Using a little DGS on a skull tracing of the SAM 4067a specimen
(Fig. 6) permits one to copy and paste elements from the left and right to create a reconstruction (Fig. 6) without reverting to the unconscious bias that attends all freehand drawings. Broom 1913 assigned this specimen to Browniella africana. Haughton 1922 considered Browniella a junior synonym and this synonymy has been accepted by all prior workers. No prior workers provided a reconstruction for accurate scoring. They just  ‘eye-balled’ the roadkill skull.

Figure 1. The SAM 4967a specimen attributed to Euparkeria. Images from Sookias et al. 2020 with colors and reconstruction added here.

Figure 6. Browniella africana, the SAM 4967a specimen attributed to Euparkeria. Images from Sookias et al. 2020 with colors and reconstruction added here.

Euparkeria capensis (Broom 1913, SAM 5867) Early Triassic, ~247 mya, 60 centimeter length is derived from the FMNH UC 1528 specimen of Youngoides (Fig. 7), a taxon ignored by Sookias et al. An unpublished paper can be found on ResearchGate.net.

The SAM 5867 specimen of Euparkeria nests between Pararchosauriformes, like Polymorphodon (Fig. 8), and all higher Euarchosauriformes like Garjainia (Fig. 9). The SAM 5867 specimen nests at the base of the Euparkeriidae, which presently include only two other tax, the SAM 4067a specimen (Fig. 6) and Osmolskina, which nest with each other (Fig. 1).

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 7. Youngoides romeri FMNH UC1528 demonstrates an early appearance of the antorbital fenestra in the Archosauriformes. This specimen is the outgroup to the Archosauriformes.

Figure 1. Skull elements of Polymorphodon.

Figure 8. Skull elements of Polymorphodon, basal to proterochampsids.

Figure 1. Garjainia at several scales and views.

Figure 9. Garjainia at several scales and views.

Osmolskina czatkowicensis (Borsuk-Biaynicka and Evans 2009), Early Triassic,

Browniella africana  (Fig. 6, SAM 4067A) is a eurparkeriid more closely related to Osmolskina in the LRT.

Sometimes additional detail comes in handy.
And Sookias et al.  2020 provided that additional detail.

Unfortunately, without a valid phylogenetic context
you won’t know the outgroups, ingroups, ancestors and descendants of any taxon under your µCT scanner. Sometimes you need a metaphorical ‘panoramic camera’ like the LRT, for that wide gamut view that minimizes taxon exclusion.


References
Broom R 1913. On the South-African Pseudosuchian Euparkeria and Allied Genera. Proceedings of the Zoological Society of London 83: 619–633.
Borsuk-Bialynicka M and Evans SE 2009. Cranial and mandibular osteology of the Early Triassic archosauriform Osmolskina czatkowicensis from Poland. Palaeontologia Polonica 65, 235–281.
Ewer RF 1965. The Anatomy of the Thecodont Reptile Euparkeria capensis Broom Philosophical Transactions of the Royal Society London B 248 379-435.
doi: 10.1098/rstb.1965.0003
Haughton S 1922. On the reptilian genera Euparkeria Broom, and Mesosuchus Watson. Transactions of the Royal Society South Africa 10, 81–88. (doi:10.1080/00359192209519270
Nesbitt SJ 2011. The early evolution of archosaurs: relationships and the origin of major clades. Bull. Am. Mus. Nat. Hist. 352, 1–292. (doi:10.1206/352.1)
Nesbitt SJ et al. 2017 The earliest bird-line archosaurs and the assembly of the dinosaur body plan. Nature 544, 484–487.
Sookias RB, Sullivan C, Liu J, Butler RJ. 2014 Systematics of putative euparkeriids (Diapsida: Archosauriformes) from the Triassic of China. PeerJ2, e658 (doi:10.7717/peerj.658)
Sookias RB 2016. The relationships of the Euparkeriidae and the rise of Archosauria. Royal Soceity open science 3, 150674. (doi:10.1098/rsos. 150674)
Sookias RB, Dilkes D, Sobral G, Smith RMH, Wolvaardt FP, Arcucci AB, Bhullar B-AS and Werneburg I 2020. The craniomandibular anatomy of the early archosauriform Euparkeria capensis and the dawn of the archosaur skull. R. Soc. Open Sci. 7: 200116.
http://dx.doi.org/10.1098/rsos.200116

https://www.researchgate.net/publication/328388486_Youngoides_romeri_and_the_origin_of_the_Archosauriformes

wiki/Osmolskina
http://reptileevolution.com/euparkeria.htm
http://reptileevolution.com/osmolskina.htm

The Solomon Islands skink (genus Corucia) enters the LRT

Today the extant Solomon Islands skink
(Corucia zebrata, Gray 1855; Figs. 1, 2) enters the large reptile tree (LRT, 1714+ taxa). It nests basal to Gymnophthlamus + Vanzosaura and between Chalcides and Sirenoscincus.

Figure 1. The Solomon Islands skink (Corucia zebrata) is the largest skink on the planet, gives birth with a placenta and lives in communities.

Figure 1. The Solomon Islands skink (Corucia zebrata) is the largest skink on the planet, gives birth with a placenta and lives in communities.

This nesting comes as no surprise.
After all, skeletally Corucia is just another widely recognized skink, albeit with some unique reproductive and social qualities (see below).

Figure 2. The skink, Corucia zebrata with DGS colors added.

Figure 2. The skink, Corucia zebrata with DGS colors added.

Do not confuse Corucia with Carusia
(Fig. 3). The two are not the same, nor are they closely related.

Figure 1. Carusia intermedia, a basal lepidosaur close to Meyasaurus now, but looks a lot like Scandensia. Note the primitive choanae and broad palatal elements. None of the data I have shows the caudoventral process of the jugal, so I added it here from the description. Same with the epipterygoid.

Figure 3. Carusia intermedia, a basal lepidosaur close to Meyasaurus now, but looks a lot like Scandensia. Note the primitive choanae and broad palatal elements. None of the data I have shows the caudoventral process of the jugal, so I added it here from the description. Same with the epipterygoid.

Corucia zebrata
(Gray 1855, Figs. 1, 2) is the extant Soloman Islands skink, the largest known extant species of skink. Long chisel teeth distinguish this herbivorous genus. The tail is prehensile. This is one of the few species of reptile to live in communal groups. Rather than laying eggs, relatively large young are born after developing within a placenta. Single babies are typical. Twins are rare according to Wikipedia.

Removing all Carusia sister taxa in the LRT
fails to shift Carusia from its traditionally overlooked node basal to squamates.

The Wikipedia entry
on the ‘clade’ Carusioidea excludes great swathes of taxa relative to the LRT, so it mistakenly suggests that extinct Carusia is a member of the Squamata. Adding pertinent taxa solves that problem, as the LRT demonstrates.


References
Gray JE 1855. (1856). New Genus of Fish-scaled Lizards (Scissosaræ), from New Guinea. Annals and Magazine of Natural History, Second Series 18: 345–346.

wiki/Solomon_Islands_skink
wiki/Carusia
wiki/Carusioidea
http://www.markwitton.com
http://tetzoo.com

https://www.researchgate.net/publication/328388754_A_new_lepidosaur_clade_the_Tritosauria

Pterodactylus antiquus extreme closeups: Tischlinger 2020

Paleo-photographer Helmut Tischlinger 2020
brings us extreme closeups of the first pterosaur ever described, Pterodactylus antiquus (Figs 1–7), in white and UV light. Here both photos of the same area are layered precisely to demonstrate the different details each type of light brings out.

The text is German.
The abstract and photo captions are duplicated in English.

Pterodactylus antiquus (Collini 1784, Cuvier 1801, 1809, Sömmerring 1812, BSP Nr. AS I 739No. 4 of Wellnhofer 1970; Late Jurassic) was the first pterosaur to be described and named.

Figure 1. Reconstruction of Pterodactylus antiquus made prior to Tischlinger 2020.

Figure 1. Reconstruction of Pterodactylus antiquus made prior to Tischlinger 2020.

From the Abstract:
“On the occasion of the reopening of the Jura Museum Eichstätt on January 9, 2020, the Bavarian State Collection for Paleontology and Geology, Munich, provided the Jura Museum with one of its most valuable fossil treasures as a temporary loan. The “Collini specimen”, first described in 1784, is the first scientifically examined and published fossil of a pterosaur and has been at the center of interest of many natural scientists since it became known… An examination of the texture of the surface of the limestone slab and the dendrites on it suggests that it does not come from Eichstätt, as has been claimed by Collini, but most likely from the Zandt-Breitenhill quarry area about 30 km east of Eichstätt. For the first time, a detailed investigation and pictorial documentation were carried out under ultraviolet light, which on the one hand document the excellent preservation of the fossil, and on the other hand show that there has obviously been no damage or manipulation to this icon of pterosaurology during the past almost 240 years.”

Figure 2. Pterodactylus wing ungual.

Figure 2. Pterodactylus wing ungual in white light and UV. Not sure why the two images are not identical, but elsewhere teeth appear and disappear depending on the type of light used.

The wing tip ungual 
appears to be present in visible light, but changes to a blob under UV (Fig. 2). Other pterosaurs likewise retain an often overlooked wingtip ungual.

In the same image
the skin surrounding an oval secondary naris within the anterior antorbital fenestra appears. Otherwise very little soft tissues is preserved.

The ‘secondary naris’ may be a new concept for some,
so it is explained below. This is not the same concept as the hypothetical ‘confluent naris + antorbital fenestra’ you may have heard about. Remember, ‘pterodactloid’-grade pterosaurs arose 4x by convergence. So each had their own evolutionary path.

Figure 3. Pterodactylus rostrum from Tischlinger 2020, colors added here. Note the original naris appears as a vestige above the maxilla tip, as in the Triassic pterosaur, Bergamodactylus and the Pterodactylus ancestor, Scaphoganthus.

Figure 3. Pterodactylus rostrum from Tischlinger 2020, colors added here. Note the original naris appears as a vestige above the maxilla tip, as in the Triassic pterosaur, Bergamodactylus and the Pterodactylus ancestor, Scaphoganthus. The shape of that narial opening is different in UV and white light.

The elements of the paper-thin rostrum
are colorized here (Fig. 3). There are subtle differences between the white light and UV images. The pink color represents a portion of the nasal that extends to the anterior maxilla and naris as in other pterosaurs and tetrapods. Did I just say naris? Yes.

Note the original naris here appears as a vestige
in its usual place above the maxilla tip, as in the Triassic pterosaur, Bergamodactylus and the late-surviving Pterodactylus ancestor, Scaphoganthus. The transition to this vestigial naris is documented in the rarely published n9 (SoS 4593), n31 (SoS 4006) and SMNS 81775 tiny transitional taxa (Fig. 4). After testing, all these turn out to be miniaturized adults traditionally mistakenly considered to be juveniles, only by those pterosaur workers who have excluded these taxa from phylogenetic analysis.

Figure 2. Click to enlarge. Painten pterosaur compared to phylogenetic sister taxa. Ornithocephalus and SMNS 81775 are the basal taxa here. Note that while everything else grows on derived taxa, the metacarpus stays the same size. The large size of the Painten pterosaur, along with the greater length of pedal digit 3 and the brevity of the metacarpus sets it apart in its own clade, of which this the first known representative. Larger than its relatives, this is an unlikely juvenile (contra Hone, see below).

Figure 4. Click to enlarge. Painten pterosaur compared to phylogenetic sister taxa. Ornithocephalus and SMNS 81775 are the basal taxa here. Note that while everything else grows on derived taxa, the metacarpus stays the same size. The large size of the Painten pterosaur, along with the greater length of pedal digit 3 and the brevity of the metacarpus sets it apart in its own clade, of which this the first known representative. Larger than its relatives, this is an unlikely juvenile (contra Hone, see below).

That’s why it is so important
to include all pterosaurs specimens as taxa in analysis. Otherwise you will miss the phylogenetic miniaturization that occurs at the genesis of major clades, the phylogenetic variation within a genus, and the evolution of new traits that have been overlooked by all other pterosaur workers.

Figure 2. Pterodactylus metacarpus including 5 digits.

Figure 5. Pterodactylus metacarpus including 5 digits. Colors added here.

The elements of the right metacarpus
are better understood and communicated when colorized (Fig. 4). Not sure where the counter plate is, but it may include some of the elements missing here, like the distal mc1. The left manus digit 5 is on that counter plate, judging from the broken bone left behind on the plate.

Figure 6. Pterodactylus antiquus pes in situ and restored to in vivo appearance.

Figure 6. Pterodactylus antiquus pes in situ and restored to in vivo appearance.

The pes is well preserved
Adding DGS colors to the elements helps one shift them back to their invivo positions. The addition of PILs (parallel interphalangeal lines, Peters 2000) complete the restoration. This is a plantigrade pes, judging by the continuous PILs that other workers continue to ignore.

Figure 6. Pterodactylus in situ under white light and UV from Tischlinger 2020. Colors added here.

Figure 7. Pterodactylus in situ under white light and UV from Tischlinger 2020. Colors added here.

Sometimes PhDs overlook certain details.
And that’s okay. Others will always come along afterward to build on their earlier observations. Tischlinger 2020 provides that excellent opportunity.


References
Collini CA 1784. Sur quelques Zoolithes du Cabinet d’Histoire naturelle de S. A. S. E. Palatine & de Bavière, à Mannheim. Acta Theodoro-Palatinae Mannheim 5 Pars Physica, 58–103.
Cuvier G 1801. [Reptile volant]. In: Extrait d’un ouvrage sur les espèces de quadrupèdes dont on a trouvé les ossemens dans l’intérieur de la terre. Journal de Physique, de Chimie et d’Histoire Naturelle 52: 253–267.
Cuvier G 1809. Mémoire sur le squelette fossile d’un reptile volant des environs d’Aichstedt, que quelques naturalistes ont pris pour un oiseau, et dont nous formons un genre de Sauriens, sous le nom de Petro-Dactyle. Annales du Muséum national d’Histoire Naturelle, Paris 13: 424–437.
Peters D 2000. Description and Interpretation of Interphalangeal Lines in Tetrapods. Ichnos, 7: 11-41
Tischlinger H 2020. Der „Collini-Pterodactylus“ – eine Ikone der Flugsaurier-Forschung Archaeopteryx 36: 16–31; Eichstätt 2020.
von Soemmering ST 1812. Über einen Ornithocephalus. Denkschriften der Akademie der Wissenschaften München, Mathematischen-physikalischen Classe 3: 89-158.
Wellnhofer P 1970. Die Pterodactyloidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Abhandlungen der Bayerischen Akademie der Wissenschaften, N.F., Munich 141: 1-133.

wiki/Pterodactylus

 

 

 

 

If you ever get ‘beaten up’ by a gang of paleontologists…

It happened over the past several months
to Xing et al. 2020 after they published in Nature on their hummingbird-sized ‘dinosaur’ in amber, Oculudentavis. Then, oops! Everyone else recognized the specimen as a lepidosaur. Last week Nature and the publicly-shamed authors retracted the paper with a fair amount of bad press.

Meanwhile, on a more personal note…
imagine examining fossils across the ocean without a science degree and ‘discovering’ four overlooked ancestors to pterosaurs (Peters 2000; Fig. 2). None had been identified before and no others have been identified since. Actually these pre-pterosaurs were recovered by adding their data to four previously published phylogenetic analyses, not by finding fossils in the field. Unfortunately (and this is true), for the next twenty years that paper, that discovery and several that followed (Peters 2002, 2007, 2009) were never cited in a supportive sense. Instead these peer-reviewed papers were shunned and ignored.

Worse yet,
imagine a gathering of PhDs rising against you online. Some call you a ‘hack’ even though you followed all the rules and did all the work with the proper citations, acknowledgements and peer review. When one studies specimens and writes papers, the furthest thing on your mind is a future with online shaming from the cancel culture.

Figure 1. Scene from Animal House when Otter walks in with roses for his hotel rendezvous, only to meet the frat boys ready to teach him a lesson.

Figure 1. Scene from Animal House after Otter walks into a hotel room with roses for his rendezvous, only to meet the five frat boys ready to deliver a little punishment.

All is not lost. Patience is the watchword here.
No one else can ‘discover’ these interrelationships (Fig. 2). They are time-stamped in the academic literature. Perhaps the best thing one can realize is: the enmity coming from other scientists turns out to be a relatively common phenomenon.

The question is:
why do some scientists demonize and shun discoverers?

The lineage of pterosaurs recovered from the large reptile tree. Huehuecuetzpalli. Cosesaurus. Longisquama. MPUM 6009.

Figure 2. The lineage of pterosaurs recovered in Peters 2000 and from the large reptile tree. Huehuecuetzpalli. Cosesaurus. Longisquama and MPUM 6009 (Bergamodactylus).

Author Jon Ronson
on the Joe Rogan Experience #668, discusses his book, ‘So you’ve been publicly shamed.’ Here he takes the antagonists’ point-of-view:

“We will reduce somebody to a label. We’ll reduce somebody to the worst tweet that they ever wrote. We’ll demonize them and then we’ll de-humanize them, because we’ve just destroyed somebody and we don’t want to feel bad about destroying them so we call them ‘sociopath’ or something.”

“It’s a whole mental trick we play on ourselves. Like, cognitive dissonance. We’re good people, but we just destroyed somebody. So how do we make sense of that?”

“So it’s all about labeling and reducing and demonizing people we don’t like.”

Then Joe Rogan pipes in:
“And it’s also an excuse to be a real asshole. Like all you have to do is find a reason to unleash your fury on people. And it’s a free shot.”

Whenever someone calls you a ‘hack’,
try to see things from their point-of-view. Do they have a point? Is there something you have to do to ‘clean up your act?’ If so, then clean up your act. Do more than is expected. Add taxa. Trace details. Show your work. Double check your results for errors. Write to experts for their advice (but be wary if they try to send you snipe hunting). After you’ve done all that, all to no avail, then consider the following…

Sometimes personal attacks are the result of unfulfilled expectations.
After all, some paleontologists spend a lot of money and many years getting a PhD only to find out professorial jobs are as rare as bird teeth. Discoveries are even harder to come by, whether in the field or by fossils occasionally sent to them.

So, it’s no wonder PhDs are pissed off
when a nobody from a small town in middle America starts harvesting the literature, adding taxa to a growing online vertebrate cladogram and making discoveries several times a week. That cladogram, the core of ReptileEvolution.com, now exceeds in size and breadth any vertebrate study ever published (samples from 1700+ fish to humans are included). New insights were recovered just by testing taxa together that have never been tested together before (like pterosaurs and lepidosaurs, Fig. 2).

The unfortunate fact is: the list of discoveries waiting to be discovered 
is limited and it gets shorter everyday. Today’s young paleontologists earned their PhDs in order to make those rare discoveries. So, imagine their wrath when an unschooled outsider showed them their expensive and time-consuming education was not really necessary, at least at this stage in paleontology. What was necessary was a comprehensive review of the literature and a single wide gamut test to reveal where taxon exclusion had resulted in traditional false positive results.

Getting back to Animal House for a moment…
Otter thought he was going to get a little romance the night he opened the door to a motel room, with the cheerful line, “It’s “Mr. Thoughtful” with a dozen roses for… you…” only to be met by a cadre of frat boys ready to pummel him (Fig. 1). Likewise, twenty years ago when I recovered four pterosaur ancestors, I thought good things would follow. Alas, that still has not happened. Nothing but ostracizing and enmity has followed.

Sadly, some of the things you learn in paleontology
are not found in textbooks. One is the extremely slow pace of acceptance in this field.

Remember it took paleontologists 150 years
to elevate the tails of tail-dragging dinosaurs and to realize birds were dinosaurs. It will take them more than twenty years to realize pterosaurs were lepidosaurs. Unlike other sciences, paleontological discoveries and recoveries, especially from outsiders, are not welcome.

So, if you make a discovery, take your punishment cheerfully
and maintain your scientific work ethic. Be patient. If you play it straight, and put the work in, you already know how this movie is going to end. Starting off, your only allies will come out of the ‘Delta House‘ fraternity, but soon you’ll have the whole audience on your side.

Good luck on your scientific journey.
Rest assured that others have been through whatever you’re going through now.

Hope this
‘futile and stupid gesture’ helps.


Postscript:
It’s no wonder that some workers thought Oculudentavis was a bird, while others thought it was a lepidosaur. After testing all known candidates, it turns out Oculudentavis was a late-surviving sister to Cosesaurus (Fig. 2), which was originally and mistakenly considered a Middle Triassic bird ancestor (Ellenberger and DeVillalta 1974). Later Peters (2000, 2007) recovered Cosesaurus as a lepidosaur and a flapping pterosaur ancestor. So, these related taxa tell the same story.

All this confusion over Oculudentavis could have been avoided
if the pterosaur community had not shunned and shamed the results of Peters 2000, 2002, 2007, 2009. Due to that suppression the bird-like lepidosaur, Cosesaurus, was not on the radar of Xing et al. and it was not tested to ascertain relationships.

And that’s how the ripples radiate.


Rarely to never cited 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.
Peters D 2000. 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 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.
Peters D 2009. A reinterpretation of pteroid articulation in pterosaurs. Journal of Vertebrate Paleontology 29:1327-1330.
Xing L, O’Connor JK,; Schmitz L, Chiappe LM, McKellar RC, Yi Q and Li G 2020. Hummingbird-sized dinosaur from the Cretaceous period of Myanmar. Nature. 579 (7798): 245–249.

wiki/Oculudentavis

Advice for would be paleontologists: stay professional!

A Blind Eye Toward Pterosaur Origins

Rachel Carson and Marie Tharp

John Ostrom: The man who saved dinosaurs

Let’s open up an old can of worms

And finally this carbon copy reply to a recent (2020) TetZoo blogpost
by PhD Darren Naish, doubling down on his earlier (2012) blogpost, “Why the World Has to Ignore ReptileEvolution.com“. This was followed by a long list of comments by a cadre of angry paleontologists.

“Well, fellas, that’s a lot to drink in. Thank you for all the attention.

ReptileEvolution.com is an online experiment in which I learn as I go. Just like a professional. True, I made over 100,000 errors in scoring or drawing over the last nine years. In understand in science that’s part of the process.

A few points worth considering:

Taxon exclusion is the issue I bring up over and over again. Just add pertinent taxa, score correctly and see what PAUP delivers. Shouldn’t be too hard. Add some placoderms to some catfish taxa. Add some caseasaurs to millerettids. And show your work.

Cau’s study on pterosaurs arising from Scleromochlus (a basal bipedal crocodylomorph) seems odd given that the hand is so small in Scleromochlus and the foot lacks a long toe 5, etc. etc. No illustrations accompany the cladogram, so we don’t know what characters were correctly or incorrectly scored for Sharovipteryx and Cosesaurus. I show my work. Ellenberger thought Cosesaurus was a Middle Triassic bird ancestor and I could not convince him otherwise. So whatever the problem is, it’s common and I’m used to it.

Yi qi: seriously? Please send data on both ulnae, both radii and the both styliforms. I will make the change to create the flying dragon if you can show valid data. Ball is now in your court.

Some hits later ‘discovered’ by others:
https://pterosaurheresies.wordpress.com/?s=heard+it+here+first&submit=Search

Figure 3. Darren Naish did not like the more precise tracing made by yours truly. He though I was seeing things. The tracing at upper left is the original published tracing by the fossil describers.

Hey, Darren, what’s wrong with that tracing of Jeholopterus skull? (Fig. 3) I provided a competing tracing (upper left hand corner). Is that all you got? After 17 years mine is still accurate and all the parts fit together in appropriate patterns. Bennett’s anurognathid skull, which you prefer, mistook a maxilla for a giant scleral ring. But the right giant scleral ring was never found. Nor were any giant scleral rings ever found on any other anurognathids. Let me know if and when you find one.

Figure 1. Chicken skull (Gallus gallus) with fused and semi-fused skull bones colorized. Postorbital = orange. Squamosal = tan. Lacrimal = brown. Prefrontal = purple. Quadrate = red.

Figure 4. Chicken skull (Gallus gallus) with fused and semi-fused skull bones colorized. Postorbital = orange. Squamosal = tan. Lacrimal = brown. Prefrontal = purple. Quadrate = red. No one else has ever attempted to do something similar.

re: that chicken skull colored photo {FIig 4}: please provide a competing image that shows what a ‘real’ chicken skull is all about. I’d like to know where the errors are so I can fix them. I prefer to use rather than create.

re: genomics vs. phenomics. Didn’t the taxon list in Afrotheria cause you to wonder, even a little bit? Gene studies produce false positives over deep time. You can test it yourself. If an amateur can do it, so can you.

If I forgot to address a favorite criticism, let me know. You guys provided a long list. At present, it’s better to be brief and to the point.

The large reptile tree (1712+ taxa) plus the pterosaur tree and therapsid skull tree all produce cladograms that recover sister taxa that actually look like each other (not like pterosaurs arising from Scleromochlus). All three are constantly being updated as I find errors. The LRT demonstrates you can lump and split 1712 taxa using only 230 multistage characters. That’s a fact. More taxa are more important than more characters. That’s a fact.

This is something the paleo community has asked for. But the order of taxa is not what you asked for. Where is the competing study? If you’ve been sitting on your hands and/or writing to Darren Naish, you’ve been wasting your time. Do what you are paid to do. Or wait until you retire and have gobs of time, like me. — David Peters”

 

 

 

 

 

 

 

 

Redondavenator enters the LRT, then exits

Several taxa tested
in the large reptile tree (LRT, 1710+ taxa; subset Fig. 2) do not remain in the LRT or the MacClade file forever. Typically they are known from very few parts, like a single jawbone. These bits and pieces enter the LRT to see where they nest, and then they exit.

In this case,
Redondavenator quayensis (Nesbitt et al. 2005; Fig. 1; NMMNH P-25615) is known from a partial snout, a partial coracoid and a partial scapula.

Figure 1. Redondavenator snout from Nesbitt et al. 2005 and colored here.

Figure 1. Redondavenator (NMMNH P-25615) snout from Nesbitt et al. 2005 and colored here.

According to the abstract
“Its exact phylogenetic position [within Crocodylomorpha] could not be determined from the preserved material, but key characters suggest a phylogenetic position near the base of Sphenosuchia.”

According to the Systematic Position section:
“Redondavenator displays the following two sphenosuchian characters: reduced external naris and nasal is not bifurcated (no descending process).

According to the Palecology section:
“the complete skull of Redondavenator is estimated to be at least 60 cm long.”  That’s six to eight times larger than in sister taxa. “Anterior sculpturing [of the snout elements] has been correlated with semi-aquatic habits as an osteological correlate of dome pressure receptors that sense motion and help orientate the animal in water.” And that may explain the size difference.

Figure 2. Subset of the LRT focusing on Crocodylomorpha. Matching Nesbitt et al. 2005, the LRT nests Redondavenator near the base of the Crocodylomorpha.

Figure 2. Subset of the LRT focusing on Crocodylomorpha. Matching Nesbitt et al. 2005, the LRT nests Redondavenator near the base of the Crocodylomorpha, but several nodes away from Sphenosuchia.

According to Wikipedia,
Sphenosuchia include Sphenosuchus, Hesperosuchus, Dibothrosuchus and the CM 73372 specimen, which does not nest in the Crocodylomorpha in the LRT, but in the Rauisuchia alongside Smok and Teratosaurus.

Figure 2. Images from Wu et al. 1993, colors and hind limbs added. Compare to skull in figure 1.

Figure 2. Images from Wu et al. 1993, colors and hind limbs added. Compare to skull in figure 1.

The Wikipedia page on Sphenosuchia does not include
several of the taxa recovered here at the base of the Crocodylomorpha, including  Pseudhesperosuchus and Lewisuchus, taxa that nest on either side of Redondavenator here (Fig. 2). Redondavenator nests close to Dibothrosuchus, but lacks the accessory fenestra between the premaxilla and maxilla, as noted by Nesbitt et al. 2005.

Figure 5. Skull of Pseudhesperosuchus, a basal bipedal crocodylomorph close to Carnufex.

Figure 5. Skull of Pseudhesperosuchus, a basal bipedal crocodylomorph close to Carnufex.

It is important to know where taxa nest,
but if a snout specimen nests close to a post-crania specimen in the LRT, then loss of resolution will result. That is why Redondavenator will not remain within the MacClade file or the LRT. Testing has already indicated its correct node and that node agrees with the original nesting.

Thanks to Dr. Lucas for sending a PDF.


References
Nesbitt SJ, Irmis RB, Lucas SG and Hunt AP 2005. A giant crocodylomorph from the Upper Triassic of New Mexico. – Paläontologische Zeitschrift 79(4): 471–478, 4 figs., Stuttgart, 31. 12. 2005.

wiki/Redondavenator

Evolution and synonyms of the hyomandibular and intertemporal

A major issue still facing paleontology and comparative anatomy
is the different names given to homologous bones in fish, reptiles and mammals. For example:

  1. the hyomandibular of fish is the stapes in tetrapods;
  2. the sphenotic in fish is the intertemporal in basal tetrapods. the opisthotic in reptiles and mammals;
  3. in fish the supraoccipital is the postparietal in stem tetrapods. That bone splits transversely to produce a postparietal and a supraoccipital in reptiles (Fig. 9);
  4. sometimes the jugal, lacrimal, nasal, maxilla and other bones also split into two or more bones. Other times they fuse together;
  5. some bones do not appear until later, de novo or by the product of a split;
  6. likewise, marginal teeth appear, disappear, fuse, unfuse, become more complex and simpler during evolution.
  7. … and that’s not counting the bones that have been traditionally mislabeled (Fig. 10).

From the genesis of the vertebrate skeleton
in Middle Silurian Birkenia (Fig. 1), a tiny hyomandibular articulates with the intertemporal dorsally and the tiny quadrate ventrally. The hyomandibular, a former dorsal gill arch segment, would ultimately evolve to become the most robust bone in the architecture of certain basal bony fish (Fig. 2) before shrinking in stem tetrapods (Fig. 6), ultimately becoming the stapes in basal reptiles (Fig. 9), and a tiny middle ear bone in mammals and humans.

Figure 2. Birkenia in situ with precursor facial bones labeled. This Middle Silurian taxon is basal to Furcacaudiformes and all other vertebrates.

Figure 1. Birkenia in situ with precursor facial bones labeled. This Middle Silurian taxon is basal to Furcacaudiformes and all other vertebrates.

In the first fish with jaws,
Chondrosteus (Fig. 2) the hyomandibular pivots to thrust the jaws forward during a bite, an action originated in tube-mouth osteostracans and sturgeons.

Figure 1. Chondrosteus animation (2 frames) in situ and reconstructed in lateral view. This is the transitional taxon linking sturgeons to bony fish + sharks.

Figure 2. Chondrosteus animation (2 frames) in situ and reconstructed in lateral view. This is the transitional taxon linking sturgeons to bony fish + sharks.

In the paddlefish ancestor,
Tanyrhinichthys (Fig. 3), the hyomandibular (deep green again) is no longer as mobile.

Figure 2b. Tanyrhinichthys skull in situ, DGS colors added here. Added after pub date. Compare to figure 2a.

Figure 3. Tanyrhinichthys skull in situ, DGS colors added here. Added after pub date. Compare to figure 2a.

The hyomandibular becomes a massive immobile element
in the Early Devonian bony fish and spiny shark  Homalacanthus (Fig. 4). It continues to link the intertemporal with the quadrate.

Figure 4. Homalacanthus in situ and reconstructed.

Figure 4. Homalacanthus in situ and reconstructed. The massive hyomandibular is dark green.

In the fish portion
of the large reptile tree (LRT, 1710+ taxa; Fig. x) we’ve just crossed the major dichotomy separating stem lobefins (many of which are still ray fins) from stem frog fish + mudskippers, sea robins and tripod fish, which also use their pectoral fins to walk along the sea floor. (Let’s save that bit of interest for another blogpost).

Figure x. Subset of the LRT, focusing on fish for July 2020.

Figure x. Subset of the LRT, focusing on fish for July 2020.

Just across the dichotomy,
the tiny (3cm) spiny shark, Mesacanthus (Fig. 5) has a slender hyomandibular with forked tips. Thereafter the hyomandibular is largely covered up by cheek bones.

Figure 1. Early Devoniann Mesacanthus in situ. This 3 cm fish is a typical acanthodian here traced using DGS methods and reconstructed. Distinct from other spiny sharks, this one lacks large cheek plates, as in the extant Notopterus (Fig. 3).

Figure 5. Early Devoniann Mesacanthus in situ. This 3 cm fish is a typical acanthodian here traced using DGS methods and reconstructed. The hyomandibular is dark green.

In the stem tetrapod and large osteolepid,
Eusthenopteron (Fig. 6) the hyomandibular (dark green) attaches to a largely submerged intertemporal (yellow-green) with little dorsal exposure. The quadrate (red) contact with the hyomandibular is only tentative.

Figure 5. Eusthenopteron hyomandibular (dark green) still linking a largely submerged intertemporal (yellow-green) and a small quadrate (red).

Figure 6. Eusthenopteron hyomandibular (dark green) still linking a largely submerged intertemporal (yellow-green) and a small quadrate (red). Here the pterygoid (dark red) is essentially vertical, distinct from most tetrapods (e.g. Figs. 7-9).

In the flattend skull of a basal tetrapod, like
Laidleria (Fig. 7), the hyomandibular / stapes is horizontal and the intertemporal does not have a dorsal exposure. The quadrate connection is broken as the stapes contacts the small posterior tympanic membrane.

Figure 6. Early tetrapod Laidleria. The intertemporal disappears from the dorsal skull and the hyomandibular / stapes dark green)  is oriented horizontally here without a quadrate connection.

Figure 7. Early tetrapod Laidleria. The intertemporal disappears from the dorsal skull and the hyomandibular / stapes dark green)  is oriented horizontally here, perhaps without a quadrate connection, but note the extent of the stapes in palate view vs. occiput view.

In the aquatic reptilomorph,
Kotlassia (Fig. 8), the hyomandibular / stapes is tiny and oriented dorsolaterally in contact with a large tympanic membrane filling a posterior notch. The intertemporal reappears on the dorsal surface of the skull and expands internally to form the paraoccipital process (opisthotic).

Figure 7. The reptilomorph, Kotlassia, skull. Note the reappearance of the intertemporal here called the prootic. The hyomandibular / stapes is tiny and dark green.

Figure 8. The reptilomorph, Kotlassia, skull. Note the reappearance of the intertemporal here called the prootic. The hyomandibular / stapes is tiny and dark green. The stapes contacts the tympanic membrane laterally.

In the basal and fully terrestrial archosauromorph,
Paleothyris (Fig. 9), the intertemporal is no longer exposed on the dorsal surface, but is exposed in occipital view, where it is called the opisthotic. The otic notch is now absent as the eardrum is reduced and relocated posterior to the jaw hinge. The former robust hyomandibular continues thereafter to shrink, becoming more sensitive to eardrum vibrations enabling a greater range of sound frequencies to be transmitted to the inner ear and brain.

Figure 8. The early archosauromorph, Paleothyris. Here the hyomandibular / stapes is oriented ventrolaterally. The intertemporal is not exposed dorsally.

Figure 9. The early archosauromorph, Paleothyris. Here the hyomandibular / stapes is oriented ventrolaterally. The intertemporal is not exposed dorsally, only occipitally where it is called the opisthotic.

On a slightly different subject:
bone misidentification by Thomson 1966

has been something of a problem ever since that publication. Here (Fig. 10) are the original bone IDs along with revised IDs on separate frames. Principally the relabeled intertemporal and parietal move behind the dorsal braincase division (Fig. 11).

Figure 2. Ectosteorhachis skull from Thomson 1966 with layers to show the brain case and palatoquadrate. Some bones are relabeled in the revised view.

Figure 10. Ectosteorhachis skull from Thomson 1966 with layers to show the brain case and palatoquadrate. Some bones are relabeled in the revised view.

Thomson 1966 erred
when he put these elements anterior to the split, probably in order to locate the pineal opening between the parietals, which is typical of tetrapods. In osteolepids and their kin the pineal opening is between the relabeled frontals anterior to the transverse cranial split (Fig. 11).

Figure 11. Eusthenopteron and Osteolepis with skull bones relabeled.

Figure 11. Eusthenopteron and Osteolepis with skull bones relabeled.

Why is this so?
Under this new labeling system the contact between the intertemporal and hyomandibular is maintained (Figs. 6, 10). Outgroups to these taxa, like Cheirolepis (Fig. 12) likewise run a portion of the postorbital over the orbit, separating the postfrontal from the orbit margin. Now the ostelepids follow that trait despite the two-part postorbital.

Figure 11. Cheirolepis is an outgroup taxon to the ostelepids that includes a postorbital that extends over the orbit, separating the postfrontal from the orbit margin.

Figure 12. Cheirolepis is an outgroup taxon to the ostelepids that includes a postorbital that extends over the orbit, separating the postfrontal from the orbit margin.

In earlier posts
on hyomandibular evolution. and juvenile Eusthenopteron (Fig. 13; Schultze 1984) corrections have now been made. This bit of relabeling is a new hypothesis awaiting confirmation from others. At present phylogenetic bracketing (Fig. 12) supports this interpretation.

Figure 1. Eusthenopteron juvenile in situ from Schultze 1984. Large plate ventral to the mandible overlaps a convex ventral margin. The quadratojugal is not labeled here. Several bones are re-labeled here.

Figure 1. Eusthenopteron juvenile in situ from Schultze 1984. Large plate ventral to the mandible overlaps a convex ventral margin. The quadratojugal is not labeled here. Several bones are re-labeled here.

For those interested,
these changes affected only 4 character traits out of 238. These scoring changes did not affect the tree topology.


References

Schultze H-P 1984. Juvenile specimens of Eusthenopteron foordi Whiteaves, 1881 (Osteolepiform Rhipidistian, Pisces) from the Late Devonian of Miguasha, Quebec, Canada. Journal of Vertebrate Paleontology 4(1):1–16.
Thomson KS 1966. The evolution of the tetrapod middle ear in the rhipidistian-amphibian transition. American Zoologist 6:379–397.
Westoll TS 1943. The hyomandibular of Eusthenopteron and the tetrapod middle ear. Transactions of the Royal Society B 131:393–414.

The ‘feathery’ anurognathid repaired with higher resolution

No one likes to trace and reconstruct
small, crushed anurognathid pterosaurs. That’s where Digital Graphic Segregation (DGS; Fig. 1) comes into play. Come to think of it, it’s rare that any pterosaur worker attempts to trace an anurognathid in precise detail before going straight to freehand (Fig. 1 upper left by Wang, Zhou, Zhang and Xu 2002; Bennett 2007).

Figure 1.  Comparing data gathering results using first-hand observation with the DGS method on the skull of Jeholopterus.. The digital outlines were then transferred into the reconstruction.

Back in 2006 I made a first attempt
at reconstructing this specimen (CAGS Z070, originally CAGS IG 02-81, Figs. 2–6), back when it was considered Jeholopterus sp. (Lü et al., 2006). That was before any other disc-head anurognathids were known and early in my studies using low-resolution images.

Those mistakes are corrected here
(Figs. 2, 3) with higher resolution images provided by Yang et al. 2018 and a fair amount of practice during the intervening years from several other disc-head pterosaurs, like SMNS 81928 (Bennett 2007) Discodactylus and Vesperopterylus.

Figure 1. The skull of the fuzzy anurognathid CAGS Z020 under DGS.

Figure 2. The skull of the fuzzy anurognathid CAGS Z070 under DGS. This is a ventral exposure. Elements match those of other anurognathids. Colors enable rapid and easy identification of every bone. The mandible is blue, shown together with the palate elements. Below in red are the quadrates. Note how low and wide the skull is.

DGS comes in handy
to segregate and reconstruct the bones of the CAGS Z070 specimen exposed in ventral view. (Fig. 2). All the elements are similar to those in other disc-head anurognathids.

Figure 2. CAGS Z020 anurognathid reconstructed in lateral view. As in other disc-head anurognathids the frog-like eyeballs likely rose above the flat skull.

Figure 3. CAGS Z020 anurognathid reconstructed in lateral view. As in other disc-head anurognathids the frog-like eyeballs likely rose above the flat skull.

Note: There are no giant eyeballs in the front half of the skull here,
nor in any anurognathid pterosaurs (Fig. 4). When Bennett 2007 mistook a maxilla for a giant scleral ring, that became gospel to a generation of lazy anurognathid workers and artists. No giant eye rings have ever been found since in any pterosaur. No matching giant eye ring was ever found on the original Bennett 2007 specimen. Better still, try to trace the bones yourself — because in science anyone can repeat a valid observation.

That being said, this is a difficult skull to trace.
Fortunately evolution works in micro steps and we’ve had several other disc-head anurognathids to look at for the Bauplan (= blueprint). You may need to practice on a few before tackling the CAGS specimen preserved in palatal / ventral view.

FIgure 3. A selection of anurognathid skulls. All follow the pattern of a small eye ring in the posterior half of the skull, except Bennett's 2007 freehand reconstruction.

FIgure 4. A selection of anurognathid skulls from 2013. All follow the pattern of a small eye ring in the posterior half of the skull, except Bennett’s 2007 freehand reconstruction.

You might remember, Yang et al. 2018
used this CAGS specimen to say pterosaurs had something like feathers all over their body. New Scientist  and The Scientist quotes several pterosaur experts in their handling of this story. All of them fell prey to ‘Pulling a Larry Martin‘ by focusing on one trait while ignoring a long list of missing taxa and all their traits. None of the following pterosaur experts traced the materials nor performed the necessary phylogenetic analyses.

  1. “I think it’s now case closed, pterosaurs had feathers.” —Steve Brusatte
  2. “Our interpretation is that these bristle-type structures are the same as the feathers on birds and dinosaurs,” —Mike Benton
  3. “This is a very important discovery, because it shows that integumentary [skin] filaments evolved in both dinosaurs and pterosaurs. That’s not surprising because they are sister groups, but it is good to know.” —Kevin Padian
  4. ”The thing that is cool is that it bolsters the idea that pterosaurs and dinosaurs are sister taxa, if they are correct in interpreting these structures as a type of feather,” —David Martill

Surprisingly taking a more critical point-of-view is Chris Bennett, “The authors’ characterization of the integumentary structures as ‘feather-like’ is inappropriate and unfortunate. It seems to me to be premature to use filamentous integumentary structures to support a close phylogenetic relationship between pterosaurs and dinosaurs.”

The CAGS specimen

Figure 5. The CAGS specimen attributed to Dendrorhyncoides and then to Jeholopterus, but is distinct from both.

In the large reptile tree
(LRT, 1707+ taxa) pterosaurs are fenestrasaur, tritosaur lepidosaurs. In other words, pterosaurs are closer to lizards than to dinosaurs. Overlooked by Benton and the others, several pterosaur outgroups (e.g. Cosesaurus, etc.) also have furry, fuzzy, feathery coverings. Perhaps thinking of the status quo, scientists who collect a paycheck have preferred not to test this twenty-year-old hypothesis of interrelationships (Peters 2000). Sometimes it takes an outsider with gobs of retirement time to expose the fallacies of traditional textbooks (= secondary profit generators).

Figure 2. Interpretation of bony and soft tissue elements in the CAGS specimen. Click to see rollover image.

Figure 6. Interpretation of bony and soft tissue elements in the CAGS specimen. Click to see rollover image.

A note on the ventral view of the CAGS skull:
The reduction of the maxillary palate bones to slender Y-shaped structures (green in Fig. 2) has not been noticed by other workers content with freehand illustrations. Earlier in 2013 the hypothesis was proposed that these slender Y-shaped bones acted like sensors in flight while feeding on flying insects. Once the fly touched the sensor, the open jaws would snap shut. Flies and mosquitos were radiating during the Triassic alongside these aerial insect eaters.

Phylogeny
Despite these several skull score changes, no shift in topology toward the other flat-head anurognathids was recovered.


References
Bennett SC 2007. A second specimen of the pterosaur Anurognathus ammoni. Paläontologische Zeitschrift 81(4):376-398.
Lü J-C, Ji S, Yuan C-X and Ji Q 2006. Pterosaurs from China. Geological Publishing House, Beijing, 147 pp.
Wang X, Zhou Z, Zhang F and Xu X 2002. A nearly completely articulated rhamphorhynchoid pterosaur with exceptionally well-preserved wing membranes and “hairs” from Inner Mongolia, northeast China. Chinese Science Bulletin 47(3): 226-230.
Yang et al. (8 co-authors including Benton MJ) 2018. Pterosaur integumentary structures with complefeather-like branching. Nature ecology & evolution

wiki/Jeholopterus

The sculpture shown on the Jeholopterus wiki page is based on my model, but they changed the skull to reflect the Bennett 2007 type skull… which is a mistake.

https://pterosaurheresies.wordpress.com/2018/12/18/pterosaur-pycnofibres-revisited-yang-et-al-2018/

https://pterosaurheresies.wordpress.com/2014/02/13/anurognathid-eyes-the-evidence-for-a-small-sclerotic-ring/

https://pterosaurheresies.wordpress.com/2013/06/21/anurognathids-and-their-snare-drum-palates/

https://www.newscientist.com/article/2188405-stunning-fossils-show-pterosaurs-had-primitive-feathers-like-dinosaurs/

https://www.the-scientist.com/news-opinion/pterosaurs-sported-feathers–claim-scientists-65220