New invalid genomic bird clade: Feraequornithes

According to Sangster and Mayr 2021,
“Recent genomic data sets have resolved many aspects of higher-level phylogenetic relationships of birds. Eleven phylogenomic studies provide congruent support for a clade formed by Procellariiformes, Sphenisciformes, Ciconiiformes, Suliformes and Pelecaniformes. This clade is here named ‘Feraequornithes’ following the rules and requirements of the PhyloCode.”

Procellariiformes = albatrosses, petrels and shearwaters.
Sphenisciformes = penguins.
Ciconiiformes = six families of storklike birds: herons and bitterns (Ardeidae), the shoebill (sole species of the Balaenicipitidae), the hammerhead (sole species of the Scopidae), typical storks and wood storks (Ciconiidae), ibis and spoonbills (Threskiornithidae).
Suliformes = gannets.
Pelecaniformes = pelicans

Here is how these five genomic clades appear
in the Large Reptile Tree (LRT, 1829+ taxa; subset Fig. 1). As you can see they are not a monophyletic clade when tested for traits. Even the genomic Ciconiformes do not produce a monophyletic phenomic clade.

Figure 1. Subset of the LRT focusing on birds. This LRT uses visible, measurable traits, not genes. Even the genomic Ciconiformes do not produce a monophyletic clade.

According to Wikipedia:
“Classically, bird relationships were based solely on morphological characteristics.”

Hopefully
paleontologists, like Sangster and Mayr, will return someday to morphological characteristics.

According to Wikipedia:
“Sibley and Ahlquist’s landmark DNA-DNA hybridisation studies (see Sibley-Ahlquist taxonomy) led to them placing the families traditionally contained within the Pelecaniformes together with the grebes, cormorants, ibises and spoonbills, New World vultures, storks, penguins, albatrosses, petrels, and loons together as a subgroup within a greatly expanded order Ciconiiformes, a radical move which by now has been all but rejected: their “Ciconiiformes” merely assembled all early advanced land- and seabirds for which their research technique delivered insufficient phylogenetic resolution.”

Turns out those landmark DNA studies
confused, rather than clarified bird interrelationships. And this may be the reason why: lateral gene transfer (Fig. 2 and YouTube video below).

Figure 2. PowerPoint frame from YouTube video presentation by John Dupre. See video link below.

References
Sangster G and Mayr G 2021. Feraequornithes: a name for the clade formed by Procellariiformes, Sphenisciformes, Ciconiiformes, Suliformes and Pelecaniformes (Aves).
Vertebrate Zoology 71: 49-53. https://doi:10.3897/vz.71.e61728
https://vertebrate-zoology.arphahub.com/article/61728/
Sibley CG and Ahlquist, JE 1990. Phylogeny and classification of birds. Yale University Press, New Haven, Conn.

https://en.wikipedia.org/wiki/Sibley%E2%80%93Ahlquist_taxonomy_of_birds

Kunpengopterus antipollicatus reconstructed and compared

A few days ago
we looked at a new pterosaur, Kunpengopterus antipollicatus (Zhou et al. 2021; BPMC 0042; early Late Jurassic) invalidating the authors’ assertion that it had an opposed thumb. Rather, and less out-of-the-ordinary, the BPMC specimen, is like all pterosaurs and most tetrapods (the ones with hands) oriented the palms side down (in flght, medial while holding a tree trunk between them). Only digit 4, the wing finger and its metacarpal, rotates the palm side posteriorly in Longsiquama + pterosaurs for flexion in the plane of the wing (Peters 2002).

Today that same pterosaur,
Kunpengopterus antipollicatus, enters the Large Pterosaur Tree (LPT, 257 taxa) with a reconstruction (Fig. 1) we can readily compare to its sister taxon, the holotype genus, Kunpengopterus sinensis (Fig. 1).

Figure 1. Kunpengopterus antipollicatus BPMC 0042 skeleton compared to reconstruction of Kunpengopterus sinensis IVPP V 16047 to scale.

Zhou et al. reported,
“BPMC 0042, an almost complete skeleton lacking the posterior region of the skull.”

Look more closely.
I was able to trace the crushed posterior region of the skull without seeing the specimen firsthand (Fig. 2). That’s why I have been promoting the use of DGS (digital graphic segregation) for crushed fossils like this one since 2003, apparently to no avail.

Figure 2. The Kunpengopterus antipollicatus skull in situ and reconstructed. Contra Zhou et al. the posterior skull is present and traceable.

Zhou et al. 2021 also had a difficult time seeing
the proximal metatarsals. The authors took the first step toward DGS by coloring the toes, but they need to go all the way and color them in transparent colors without black outlines. Then they need to reconstruct the pes from the elements traced. The complete pes reconstruction is validated by the continuous PILs (parallel interphalangeal lines).

Figure 3. Kunpengopterus antipollicatus from Zhou et al. (lower right) compared to DGS method (lower left) which enables a reconstruction from simply moving the parts color by color (top).

Zhou et al. were confident
that the BPMC skeleton was complete and unaltered, but the two feet don’t match (Fig. 4). That’s a sign that at least something was altered. This is where reconstructions (Figs. 1-4) become helpful, not only for discovery, but for sharing data at a glance. There were 12 co-authors for this paper and none were given the assignment to be the Tenth Man. The danger of that is for grad students and post-docs disagreeing with their professor risks grades, recommendations, assignments, collaborations, travel vouchers and other perks and punishments. The professors I know don’t like to be wrong. When confronted with contrary evidence some of them become silent. Others revert to middle-school name-calling. Professors and post-grads think their reputation is at stake and maybe it is. That’s why we have to have Independent Researchers who are not swayed by reputation, salary or any other influence other than the evidence.

Figure 4. The two pedes of the BPMC specimen compared. Note the differences overlooked by Zhou et al. probably because they did not create a reconstruction of their tracing.

Rarely do PhDs want to check the work of their colleagues.
There’s no pay-off because there’s no chance for discovery. They think their colleagues are accurate and cover all the bases. Given that scenario, it enters the realm of unattached amateurs to check the work of PhDs. Unfortunately and too often errors of omission, like taxon exclusion, or overlooked bits and pieces (Figs. 3, 4) are easily found by amateurs just putting forth a little more effort in areas the PhDs and their textbooks currently consider irrelevant.

Since the Zhou et al. paper touted a false hypothesis in its headline
(the opposed thumb), it should be retracted and edited to simply describe with more accuracy the very typical BPMC specimen as it is, without headline-grabbing embellishment. Otherwise this pterosaur myth, like so many others, will enter the academic universe without apology.

References
Peters D 2002. A New Model for the Evolution of the Pterosaur Wing – with a twist. – Historical Biology 15: 277–301.
Zhou X et al. (11 co-authors) 2021. A new darwinopteran pterosaur reveals arborealism and an opposed thumb. Current Biology (2021), https://doi.org/10.1016

BPMC = Beipiao Pterosaur Museum of China, Beipiao, Liaoning Province, China.

Arapaima enters the LRT basal to Salmo, far from Osteoglossum

Arapaima gigas (Cuvier 1812, Schinz 1822, Müller 1843, originally Sudis gigas; up to 2-3m; Figs. 1, 2) is the extant arapaima, one of the largest living freshwater fish.

Traditionally Arapaima is considered a member
of the Osteoglossiformes (bony tongues) and arapaima does have a bony tongue. Other traditional osteoglossiformes include arowanas like Osteoglossum (Fig. 3), featherbacks, like Notopterus, knifefish like Gymnotus and mormyroids like Mormyrus.

Figure 1. Arapaima nests between Amia and Salmo in the LRT and is the largest of the three.

After testing
in the large reptile tree (LRT, 1827+ taxa) Arapaima nests between the bowfin, Amia, and the salmon, Salmo as a basal rayfin fish. This fish-eating, air-breather with gills has a thick armor of tough scales to fend off piranha attacks. It lives in oxygen-poor remnants of the Amazon River and eats a wide variety of fish, crustaceans, fruits, seeds and insects. Hatchlings are protected within the mouth of the male, as in the unrelated by neighboring Osteoglossum.

Figure 2. Arapaima in vivo and skeletal.

Both Osteoglossum and Arapaima occupy a similar niche
in today’s Amazon River. Both have many traits in common by convergence, likely due to this similar niche. The LRT is strong enough to lump and split 1827 often convergent taxa despite using only 235 traits originally designed for reptiles. Not bad. It’s not falling apart yet, despite the predications of PhDs from years ago who should know better.

This breaking up of the traditional membership of Osteoglossiformes
echos similar breakups in the LRT of Batoidea, Cetacea, Ornithodira (= Avemetatarsalia) and Pseudosuchia. This is what happens when you simply add taxa.

Figure 3. Osteoglossum, the arowana, an Amazon River predator, is unrelated to Arapaima (Figs 1, 2), despite several convergent traits likely due to similar Amazon River niche.

The breakup of the Osteoglossiformes
appears to be a novel hypothesis of interrelationships. If not, please provide an earlier citation so I can promote it here. Don’t send DNA studies. We already know they don’t work in deep time studies.

References
Cuvier G 1816. Le Règne Animal distribué d’après son organisation pour servir de base à l’histoire naturelle des animaux et d’introduction à l’anatomie comparée. Les reptiles, les poissons, les mollusques et les annélides. Edition 1 [Work generally dated 1817; published before 2 December 1816 according to Roux, Journal of the Society for the Bibliography of Natural History 8(1): 31]. 2( i-xviii): 1-532, [Pls. 9-10, in v. 4].
Müller JP 1843. Beiträge zur Kenntniss der natürlichen Familien der Fische. Archiv für Naturgeschichte, 9: 292–330.

wiki/Arapaima
wiki/Osteoglossiformes

False claim: a Jurassic pterosaur with an opposable thumb

Part 2
dedicated to this specimen can be found here. It includes details, reconstructions and comparisons.

Zhou et al. 2021 falsely claim
to have found a one and only ‘opposed thumb’ in the rather common fossil of the rather typical early Late Jurassic darwinopteran (= wukongopterid) pterosaur, Kunpengopterus ( BPMC 0042; Fig. 1).

Figure 1. Kunpengopterus in situ, from Zhou et al 2021.

Many pterosaurs are preserved with fingers disarticulated and flattened.
So the Zhou et al. report is much adieu about nothing. The authors state, “Concerning the new species, the most striking feature of the holotype is that, on both sides, the pollex is preserved in an opposed position, with its palmar side facing the palmar side of the other digits (Figures 1 and 2). Hypotheses of taphonomic digit flipping (preservational alteration of digit position) are excluded, as well as of artificial alteration of the specimen.”

The authors should NOT have excluded ‘alteration of the digit position’. This situation is so common it is typical of crushed pterosaurs.

According to Zhou et al.
“its osteological configuration is similar to that observed in the avian reversed hallux.”

Only as preserved. This is youthful / wishful thinking and / or headline seeking. When the fingers are reconstructed to their in vivo positions (Fig. 4) all of the Zhou et al. positional hypotheses are shown to be invalid.

Problem #1:
The authors think digits 2 and 3 are not rotated. They think this pterosaur flew with the palmar side of digits two and three anterior (Figs. 2, 3, 7), not ventral (in flight, Fig. 4), as in all other tetrapods and pterosaurs. The authors don’t recognize the taphonomic rotation in digits 2 and 3, or digit 1. The fingers are all rotated and disarticulated during crushing to the plane of the wing in this specimen and most other pterosaur fossils.

Problems #2:
By rotating digit 1 in the opposite direction to digits 2 and 3, digit 1 would have interfered with the plesiomorphic ability of using all three claws in unison (Fig. 6) like tree-climbing lizards do (Fig. 5). The distal end of metacarpal 1 is not shaped like an extended cylinder permitting much more extension than shown in the fossil, so it would always get in the way. The distal end of metacarpal 1 is indeed slightly angled to permit digit 1 to be used at a slight angle during tree clinging, as in tree-climbing lizards (Fig. 5).

Figure 2. Kunpengopterus manus with color overlay. P> = palmar side.

Zhou et al. state,“The distal half of metacarpal I torsions on its long axis, with the palmar surface suffering a dorsomedial deflection (or supination) of 150. The distal articulation of metacarpal I is thus torsioned, affecting the orientation of the pollex.”

This is a misinterpretation not supported by the data.

Figure 3. Frame 1 µCT scans from Zhou et al. Frame two modified with captions and fingers reconstructed for a typical pterosaur and a typical tetrapod oriented to flex toward the palmar surface. Nothing about this is out of the ordinary.

The authors did not cite
Peters 2002, who showed how pterosaur claws were used in unison to cling to tree trunks of any diameter (Fig. 6), as in modern climbing lizards (Fig. 5) and presumed for basal birds with claws, like Archaeopteryx.

Figure 4. From the uncited Peters 2002 showing a typical pterosaur manus in anterior and dorsal views. The dorsal view shows the wing finger at three stations from folded to extended.

Figure 5. From Peters 2002 showing two arboreal lizards on tree truniks. Note the positions of the medial three fingers and the medial three toes. Compare to figure 6. Grasping is not necessary at this scale when you have such long, curved, sharp claws to slightly dig into tree bark.

Figure 6. From Peters 2002 showing how a typical basal pterosaur would cling to a tree and still be able to extend and flex the wing finger without interference. Pedal digit 5 is not associated with a uropatagium.

Figure 7 an illustration from Zhou et al. 2021 showing their interpretation in vivo. Note the invalid and impossible supination of the wrist to orient fingers 2 and 3 palms anterior. Humans can do this. Pterosaurs cannot. Finger 1 is at right angles to these two, not in the plane of the wing as proposed by Zhou et al. And where is the plane of the wing here? It’s all over the place! Compare to figure 6 where the wing folds up completely in the plane of the wing.

Lead author Xuanyu Zhou
is a young PhD student (according to a Google search) with a previous pterosaur paper on the istiodactylid, Nurhachius.

When young PhD students make basic mistakes
it may be appropriate to blame their education, apparently still stuck in the dark ages. Not sure if the young authors were told to avoid Peters 2002 or were not aware of that citation due to the last few decades of anti-Peters propaganda. Professor emeritus U of Copenhagen, Niels Bonde, is a co-author, so there was an elderly guiding hand.

If you know a PhD student
who is going down the wrong path, try to gently steer them straight, as I am attempting to do here. Once a paper is published, the embarrassment that ensues will last a lifetime.

References
Peters D 2002. A New Model for the Evolution of the Pterosaur Wing – with a twist. – Historical Biology 15: 277–301.
Zhou X et al. (11 co-authors) 2021. A new darwinopteran pterosaur reveals arborealism and an opposed thumb. Current Biology (2021), https://doi.org/10.1016/j.cub.2021.03.030

PR from Birmingham, UK

http://reptileevolution.com/pterosaur-wings.htm

The ‘tailed’ frog, Ascaphus, enters the LRT

Everyone knows so-called ‘tailed frogs’ are primitive,
but not more primitive than Triassicus, the long-torso, short-leg frog from the Triassic. Ascaphus (Figs. 1, 2) enters the LRT alongside Rana, the only other extant frog in the large reptile tree.

Figure 1. Male Ascaphus truei in vivo. Not a true tail, that tissue is an extension of the cloaca for internal insemination.

The semicircular skull with enormous orbits
in Ascaphus (Fig. 2) recalls Triassicus. The absence of lacrimals and the reduction of other circumorbital bones is apomorphic, or at least not shared with Rana.

Figure 2. Ascaphus skeletons in dorsal view. Skull and wrist colors applied here. Note five carpals are present but only four fingers were present, the plesiomorphic number for basal tetrapods.

Ascaphus truei
(Stejneger 1899) is the extant tailed frog. The so-called tail is only found in males and is an extension of the cloaca for internal fertilization, the primitive state. More dorsal and lumbar vertebrae are present than in Rana (below).

Figure 3. Rana skull in several views.

Rana catesbeiana
(Linneaus 1758, Shaw 1802) extant, bull frog. Derived from a sister to Triadobatrachus, Rana is the last of this lineage and includes some 90 species.

Distinct from Triadobatrachus, the skull of Rana is more spade-shaped in dorsal view. The nasals extend laterally to the maxilla. The squamosal is reduced to a frame for the eardrum.

The presacral count is further reduced to 9. The tail vertebrae are fused into a single long bone, the urostyle, following the sacral vertebrae, but note that while the urostyle is long, it lies completely between the ilia and does not extend beyond the ischium.

Figure 4. Rana skeleton in several views. Note the fewer vertebrae.

A cartilaginous element,
the suprascapula, extends dorsal to the scapula and roofs over the first few dorsal ribs. The radius and ulna fuse. The hand is larger. The thumb is absent. Only a vestigial stub sometimes remains of metacarpal 1. Digit 2 of the manus has one fewer phalanx probably by fusion. Digits 3 and 4 have two fewer phalanges.

The ilium is elongated to half the torso length. The femur is gracile and elongated. The tibia and fibula are fused. The tibiale (astragalus) and fibulare (calcaneum) further elongate the foot. No trace of pedal 2.1 is present. A small medial carpal spur is present.

References
Stejneger LH 1899. Type species: Ascaphus truei. Proceedings of the US National Museuem 21:899.

wiki/Triadobatrachus
wiki/bull frog
wiki/Rana
wiki/Tailed_frog

Dissacus enters the LRT transitonal to mesonychids from oreodonts

Updated October 18, 2021
with a review that nests Dissacus transitional from oreodonts to mesonychids.

According to Wikipedia
“Dissacus (Cope 1881, Fig. 1) is a genus of extinct carnivorous jackal to coyote-sized mammals within the family Mesonychidae, an early group of hoofed mammals that evolved into hunters and omnivores. Their fossils are found in Paleocene to Early Eocene aged strata in France, Asia and southwest North America, from 66–50.3 mya, existing for approximately 15.7 million years.”

Figure 1. Dissacus skull, colors added here.

Earlier
in the large reptile tree (LRT, 1826+ taxa) Dissacus nested as the base of the Borophagus, Speothos, Tremarctos clade within Carnivora. New scoring of this taxon and related taxa now nests Dissacus between oreodonts and mesonychids.

Figure 2. Subset of the LRT focusing on derived placentals and including Dissacus between oreodonts and mesonychids.

Geisler and McKenna 2007
described the partial remains of Dissacus zanabazari (MAE−BU−97−13786; Fig. 1) from Mongolia. The authors included in their cladogram several taxa not related to mesonychids (e.g. Hapalodectes hatangensis a tree shrew, Diacodexis an artiodactyl, Andrewsarchus an anagalid, Eoconodon an untested mandible and Arctocyon, a marsupial creodont). No oreodonts or basal terrestrial herbivorous placentals, like Phenacodus, were tested.

References
Cope ED 1881. Notes on Creodonta. American Naturalist 15: 1018–1020.
Geisler JH 2001. New morphological evidence for the phylogeny of Artiodactyla, Cetacea, and Mesonychidae. American Museum Novitates 3344, 1-53.
Geisler J and McKenna MC 2007. A new species of mesonychian mammal from the lower Eocene of Mongolia and its phylogenetic relationships. Acta Palaeontologica Polonica 52, 189-212.
O’Leary MA 1998. Phylogenetic and morphometric reassessment of the dental evidence for a mesonychian and cetacean clade. In Thewissen, J. G. M. (ed) The Emergence of Whales: Evolutionary Patterns in the Origin of Cetacea. Plenum Press (New York), pp. 133-161.
O’Leary MA 1999. Parsimony analysis of total evidence from extinct and extant taxa and the cetacean-artiodactyl question (Mammalia, Ungulata). Cladistics 15, 315-330.
O’Leary MA 2001. The phylogenetic position of cetaceans: further combined data analyses, comparisons with the stratigraphic record and a discussion of character optimization. American Zoologist 41, 487-506.
Solé F, Godinot M, Laurent Y, Galoyer A and Smith T 2018. The European Mesonychid Mammals: Phylogeny, Ecology, Biogeography, and Biochronology. Journal of Mammalian Evolution. 25 (3): 339–379.
TetZoo blogpost. Mesonyx and the other mesonychid mesonychians (mesonychians part IV). Although posted by a PhD, what is written here is untested by the poster, so is more journalism than paleo.

Carpus evolution in human ancestry back to basal reptiles

Out of 3400 prior posts
only two prior posts focused on carpals. One looked at the prepollux (radial sesamoid) of pandas and the pteroid + preaxial carpal of pterosaurs. Two looked at whale carpals here.

At present
the large reptile tree (LRT, 1825+ taxa) includes relatively few carpal traits, and none related to the migration of the pisiform and carpal 4 in mammals (see below). Crocodylomorphs elongate the proximal carpals. Many taxa do not ossify the carpals. As mentioned above, fenestrasaur centralia migrate  to become the pteroid and preaxial carpal in pterosaurs. So some carpals are more interesting than others.

Figure 1. (Left) Diplovertebron right manus dorsal view. Carpal elements colored. (Right) Thrinaxodon right manus dorsal view. Some elements rotated to fit reconstruction. Some phalanges are reduced to discs in Thrinaxodon on their way to disappearing in mammals.

I was also interested
in the origin of the styliform process on the human ulna. It is located where the pisiform is located in Diplovertebron (Fig. 1) a basal archosauromorph amphibian-like reptile. And thus began a look at sample taxa in the lineage of humans.

The next step
was the basal cynodont, Thrinaxodon (Fig. 1). Here the elements are larger, link closer to one another and are better ossified. Some phalanges are reduced to discs in Thrinaxodon on their way to disappearing in mammals.

Figure 2. Right manus of the platypus, Ornithorhynchus (left) and early therian, Eomaia (right). Carpal elements colored. Note the disappearance (or fusion) of distal tarsal 4 in Eomaia along with the centralia.

The next step in carpal evolution is represented by the basalmost mammal,
Ornithorhynchus (Fig. 2), the platypus. Here distal tarsal 5 is ventral to the lateral centralia. The pisiform is tiny. The radiale and ulnare completely cap the radius and ulna. The platypus is a highly derived monotreme, not a basal taxon.

The enlargement of the distal radius width
relative to the distal ulna width begins with Eomaia (Fig. 2), a basal therian. So does the enlargement of distal carpal 5, taking the place of distal carpal 4.

The migration of tiny distal 4 to the palmar surface
is documented in the evolution of human carpals (Fig. 4), but probably originated with Eomaia (Fig. 2) where distal tarsal 4 is not diagrammed.

At this point it is worth noting
that mammal carpals have different names than those of other tetrapods. Here are the mammal homologs (which we will ignore):

Proximal Tarsals:

• • Radiale = Scaphoid (lavendar)
  • Intermedium = Lunate (tan)
  • Ulnare = Triquetrum (dull pink)
  • Pisiform = Pisiform (yellow green)

Centralia

• • Medial Centralia = Prepollex (blue gray)
  • Lateral Centralia = Lateral Centralia (blue gray)

Distal Tarsals:

• • DT1 = Trapezium (yellow)
  • DT2 = Trapezoid (orange)
  • DT3 = Capate, magnum (green)
  • DT4+5 = Hamate, unciform (4= blue, 5=purple)

Figure 3. Right manus dorsal view of basal tree shrew, Ptilocercus (left), and basal lemur, Indri (right). Carpal elements colored.

The next step in carpal evolution is represented by a basal placental,
Ptilocercus (Fig. 3), a tree shrew close to the base of the gliding and flying mammals. The fusion of distal tarsal 3 to the medial centrale is seen in Ptilocercus and its descendants. The ulna has a styloid process and the pisitorm extends laterally. Distal tarsal 1 is medially elongate to support a diverging thumb, further supported by the medial centralia.

Turns out the styloid process of the ulna
is not a fused carpal, but a novel outgrowth of the distal ulna appearing in basal placentals. The styloid process may have something to do with the ability of basal placentals to laterally rotate the manus for tree climbing in any orientation, including inverted, and to create a stop to prevent further rotation. Bats take this ability to its acme during wing folding.

Figure 4. Manus of human (Homo) in dorsal (left) and ventral/palmar (right) views. Carpal elements colored. Carpal 4 and pisiform palmar only. Compare to Diplovertebron (Fig. 1) in which so little has changed, including relative finger length.

The final step in carpal evolution
takes us from the lemur, Indri (Fig. 3) to the human, Homo (Fig. 4). Here a ventral (palmar) view of the manus is also provided so we can finally see the ultimate destination of distal tarsal 4.

Before finishing this blog post
scroll back and forth between figures one and four to see how close the human hand and all of its proportions so greatly resembles that of a very basal ampibian-like reptile. Even the relative finger length is the same. This is probably the most important takeaway today. The LACK of change is the news story here. Dinosaurs, horses and snakes cannot make the same statement.

There is no reason to continue using
the mammal specific identification of the carpals in paleontology when those bones are homologs to tetrapod wrist bones going back to the Devonian. Medical communities should also start using tetrapod homologs and let the analog identities fade into history.

Simply put:
There are five distal carpals named one through five in tetrapods. Some of them fuse with other carpals. There are three centralia. Some of these fuse with other carpals. Tetrapods have three proximal carpals. Their names are easy. The radiale is on the radius. The ulnare is on the ulna. The intermedium is intermediate between them. These tend not to fuse with other carpals, at least in basal placentals. And finally the pisiform appears by itself on the lateral margin sometimes in contact with the distal ulna sometimes not.

On a similar note,
we supported earlier efforts to provide tetrapod homologs for fish skull bones here. Make things simple. There is enough hard work out there without needlessly translating bone identities.

---

References
Hamrick MW and Alexander JP 1996. The Hand Skeleton of Notharctus tenebrous (Primates, Notharctidae) and Its Significance for the Origin of the Primate Hand. American Museum Novitates 3182, 20pp.
Kielan-Jaworowska Z 1977. Evolution of the therian mammals in the Late Cretaceous of Asia. Part n. Postcranial skeleton in Kennalestes and Asioryctes. In: Z. Kielan-Jaworowska (ed.) Results Polish Mongolian Palaeont. Expeds. VIII. – Palaeont, Polonica, 37, 65-84.
Peters D 2009. A reinterpretation of pteroid articulation in pterosaurs. Journal of Vertebrate Paleontology 29:1327-1330.
Salesa MJ, Antón M, Peigné S and Morales J 2005. Evidence of a false thumb in a fossil carnivore clarifies the evolution of pandas. Proceedings of the National Academy of Sciences of the United States of America. abstract and pdf

Fossiomanus and Jueconodon enter the LRT as pre-mammal diggers

As the headlines reported,
(see below) these two late-surviving pre-mammals lived under the feet of Early Cretaceous dinosaurs and probably only came out after dark.

From the Mao et al. 2021 abstract:
“Mammaliamorpha comprises the last common ancestor of Tritylodontidae and Mammalia plus all its descendants. Tritylodontids are nonmammaliaform herbivorous cynodonts that originated in the Late Triassic epoch, diversified in the Jurassic period and survived into the Early Cretaceous epoch. Eutriconodontans have generally been considered to be an extinct mammalian group, although different views exist.”

“Here we report a newly discovered tritylodontid and eutriconodontan from the Early Cretaceous Jehol Biota of China. Eutriconodontans are common in this biota, but it was not previously known to contain tritylodontids.”

Confirmation on those points!
In the large reptile tree (LRT, 1825+ taxa; subset Fig. 4) Fossiomanus nests with Oligokyphus and the tritylodonts. The other new burrowing pre-mammal, Jueconodon nests with Liaocondon, and other eutriconodonts close to Gobiconodon and Repenomamus.

Figure 1. Fossiomanus in situ in two ventral views, plus manus, pes and pelvis reconstructed. Teeth colored. Taphonomically shifted pectoral girdle repaired on right. The current view of the skull material prevents a reconstruction at this time.

Figure 2. Skull of Jueconodon based on data from Mao et al. 2021.

Mao et al. continue:
“These fossils shed light on the evolutionary development of the axial skeleton in mammaliamorphs, which has been the focus of numerous studies in vertebrate evolution and developmental biology. The phenotypes recorded by these fossils indicate that developmental plasticity in somitogenesis and HOX gene expression in the axial skeleton—similar to that observed in extant mammals—was already in place in stem mammaliamorphs. The interaction of these developmental mechanisms with natural selection may have underpinned the diverse phenotypes of body plan that evolved independently in various clades of mammaliamorph.”

Figure 3. Cladogram from Mao et al. 2021, color overlays added here to show how LRT divides these clades. Compare to figure 4.

Usually, ‘No hypotheses like this can proceed without first establishing a valid phylogeny.’ Parts of Mao et al. match the LRT. Unfortunately, Mao et al. follow invalid academic tradtion as they also include and therefore nest multituberculates with pre-mammals, rather than with rodents and plesiadapiformes in the gnawing clade, Glires. Just add pertinent taxa to resolve this problem. So far PhDs have been reluctant to do this and so the myth continues untested except here.

Mao et al. nest Jueconodon between Liaoconodon and Chaoyangodens (Fig. 3). In the LRT (Fig. 4) Jueconodon also nests with Liaoconodon, but Chaoyangodens nests as a monotreme mammal, basal to the echidna and platypus (Tachyglossus and Ornithorhynchus).

Mao et al. nest Fossiomanus with Kayentatherium, basal to four other tritylodontids including Tritylodon and Oligokyphus among mutually tested taxa. In the LRT (Fig. 4) Fossiomanus nests similarly.

Figure 4. Subset of the LRT focusing on pre-mammals with the addition of Fossiomanus and Jueconodon. Compare to original cladogram in figure 3 and to the LRT for a look at related taxa.

Mao et al. mention Liaoconodon often:

1. “The triangular shape of the skull may have been exaggerated by the crush of
   the specimen, but compared to those that have the similar preservation, such as Jeholodens, Liaoconodon, and Chaoyangodens, the triangular shape of Jueconodon is distinctive.
2. The morphology of the mandible is similar to those of other eutriconodontans, such as Liaoconodon (Meng et al., 2011). Given that Liaoconodon was interpreted as a semiaquatic animal (Chen and Wilson, 2015), the similar mandible in both species indicate that the lower jaw and teeth of Jueconodon were not specialized for digging.
3. The ossified Meckel’s cartilage on each side is preserved but displaced from its anatomical position. This suggests that the transitional mammalian middle ear, as best shown in Liaoconodon (Meng et al., 2011), was present in the fossorial eutriconodontans.“

Figure 5. Skull of Liaoconodon.

Figure 6. Liaoconodon in situ.

Mao et al. report, “the Manda cynodont and mammaliaforms that are considered terrestrial.
Compared to extant mammals, Fossiomanus sinesis is superficially similar in body size and shape to the Cape dune mole-rat Bathyergus suillus, the largest subterranean scratch-digger species of the African mole-rats (Montoya-Sanhueza et al., 2019). However, they differ fundamentally in the axial skeleton in that mole-rat has the rodent body plan with the ancestral PV count of mammals.”

References
Mao F-Y, Zhang C, Liu C-Y and Meng J 2021. Fossoriality and evolutionary development in two Cretaceous mammaliamorphs. Nature (advance online publication)
doi: https://doi.org/10.1038/s41586-021-03433-2
https://www.nature.com/articles/s41586-021-03433-2

wiki/Fossiomanus
wiki/Cape_dune_mole-rat

http://www.sci-news.com/paleontology/fossiomanus-sinensis-jueconodon-cheni-09534.html

https://www.amnh.org/explore/news-blogs/research-posts/burrowing-mammal-ancestors-discovered

Jurassic salamander, Chunerpeton, enters the LRT

In the large reptile tree (LRT, 1823+ taxa) 18 cm Late Jurassic Chunerpeton nests with Andrias, the extant giant salamander from China. No surprise.

Chunerpeton tianyiense (Gao and Shubin 2003; Rong et al. 2021; CAGS-IG-02051; Late Jurassic) is an ancestor of Andrias with several primitive traits. The diagrams by Rong et all do not recognize several bones colorized here.

Figure 2. Skull of Andrias updated.

References
Gao KQ and Shubin NH 2001. Late Jurassic salamanders from northern China. Nature 410, 574–577.
Rong Y-F, Vasilyan D, Dong L-Pand Wang Y 2021. Revision of Chunerpeton tianyiense (Lissamphibia, Caudata): Is it a cryptobranchid salamander? Palaeoworld in press.

Portunatasaurus almost enters the LRT with dolichosaurs, not mosasaurs

Too few traits are present
for Portunatasaurus (Figs. 1–3) to be entered into the LRT without loss of resolution, but that shouldn’t stop us from figuring out what it is and what it isn’t.

Figure 1. Portunatasaurus compared to stem mosasaur, Aigialosaurus and to marine stem snake, Aphanizocnemus.

From the Mekarski et al. 2019 abstract:
“A new genus and species of plesiopedal mosasauroid, Portunatasaurus krambergeri, from the Cenomanian–Turonian (Late Cretaceous) of Croatia is described.”

Ooops. Taxon exclusion rears its ugly head again. In the large reptile tree (LRT, 1823+ taxa) Portunatasaurus (Fig. 1) is closer to aquatic snake ancestors, like Aphanizocnemus (Fig. 1), than a “plesiopedal mosasaurid.” Even with so few traits to test, moving Portunatasaurus closer to mosasaurs and aigialosaurs adds 4 steps. In the LRT Aphanizocnemus nests as a snake ancestor: a marine varanoid dolichosaur scleroglossan squamate.

Figure 2. Portunatasaurus diagram with corrections. Note the robust ribs, as in dolichosaurs. Mosasaurs and aigialosaurs have gracile ribs, a trait not tested in the LRT.

Mekarski et al. 2019 continue:
“An articulated skeleton, representing an animal roughly a meter long was found in 2008 on the island of Dugi Otok. The specimen is well represented from the anterior cervical series to the pelvis.”

There is no lumbar area in the Mekarsi et al. diagram (Fig. 2). Moving the pelvic area posteriorly to give Portunatasaurus a lumbar area agrees with other clade members. Note the robust ribs in Portunatasaurus, as in dolichosaurs. Mosasaurs and aigialosaurs (Fig. 1) have gracile ribs, a trait not tested in the LRT.

Figure 3. Portunatasaurus manus (right) and reconstructed with PILs (left).

Mekarski et al. 2019 continue:
“Preserved elements include cervical and dorsal vertebrae, rib fragments, pelvic fragments, and an exquisitely preserved right forelimb. The taxon possesses plesiomorphic characters such as terrestrial limbs and an elongate body similar to that of basal mosasauroids such as Aigialosaurus or Komensaurus, but also shares derived characteristics with mosasaurine mosasaurids such as Mosasaurus.”

Note: the authors appear to have omitted dolichosaurs from consideration. Dolichosaurs are not mentioned in the abstract. Let me know if this is an error. I have contacted Mekarski for a PDF.

“The articulated hand exhibits a unique anatomy that appears to be transitional in form between the terrestrially capable aigialosaurs and fully aquatic mosasaurines, including 10 ossified carpal elements (as in aigialosaurs), intermediately reduced pro- and epipodials, and a broad, flattened first metacarpal (as in mosasaurines).

Note: the authors appear to be not looking at dolichosaurs. Whenever an author uses the word “unique” it is a good bet that pertinent taxa have been omitted because nothing in “unique” in evolution. What is unique for one clade is commonplace in another.

“The new and unique limb anatomy contributes to a revised scenario of mosasauroid paddle evolution, whereby the abbreviation of the forelimb and the hydrofoil shape of the paddle evolves either earlier in the mosasaur lineage than previously thought or more times than previously considered.”

Authors rarely consider the number one problem in paleontology: taxon exclusion. They prefer those headline-grabbing words like “unique” so they can postulate newer hypotheses ‘than previously considered.” Well, don’t we all… but these authors/PhDs are paid to do this and not make mistakes in taxon exclusion that an amateur with an online cladogram can pick apart without actually seeing the specimen.

“The presence of this new genus, the third and geologically youngest species of aigialosaur from Croatia, suggests an unrealized diversity and ecological importance of this family within the shallow, Late Cretaceous Tethys Sea.”

I assume it is a coincidence that mosasaur ancestors and unrelated snake ancestors were both found in the earliest Late Cretaceous strata surrounding today’s Mediterranean Sea. Let me know of Mekarski et al. tested dolicohosaurs in their cladogram. I had access only to the abstract and some figures.

The paper [PDF] just arrived.
No phylogenetic analysis is provided. Aphanizocnemus is not mentioned. Other dolichosaurs are compared.

---

References
Mekarski MC et al. 2019. Description of a new basal mosasauroid from the Late Cretaceous of Croatia, with comments on the evolution of the mosasauroid forelimb. Journal of Vertebrate Paleontology. 39: e1577872. doi:10.1080/02724634.2019.1577872.

wiki/Portunatasaurus