A small tapir-like ‘oreodont’ from North America enters the LRT with astrapotheres from South America

This could be an overlooked interrelationship.
The large reptile tree (LRT, 1978+ taxa; Fig. 4) currently nests North American tapir-like Brachycrus (Figs. 1–3) with a similar, though much larger South American tapir-like taxon, Astrapotherium (Fig. 1).

Figure 1. Astrapotherium to scale with the smaller Brachycrus and transitional Astraponotus.

According to Wikipedia,
“Brachycrus is an extinct genus of oreodont, of the family Merycoidodontidae, endemic to North America.”

According to Wikipedia,
“Astrapotherium (“lightning beast”) is an extinct genus of South American mammals that… was unrelated to elephants or tapirs, but was instead related to other extinct South American ungulates.”

According to the LRT, neither is correct.

Figure 2. Brachycrus skull in several views.

Also added to the LRT
is the Brachycrus-sized transitional astrapothere, Astranopodus (Figs 1, 3).

Figure 3. Astraponotus skull in 3 views to scale with Brachycrus.

Astrapotherium magnum
(Burmeister 1879, Hatcher 1901; Paleocene-Miocene, 59-12 mya; 3m long; Fig. 1) was considered a South American ungulate and a member of the order, Astrapotheria, by the authors of Wikipedia. They report, “The history of this order is enigmatic.” Here (Fig. 4) Astrapotherium nests with Meniscotherium, in a clade between Titanoides and Phenacodus. Like a hippo, the large and ever-growing curved canines of Astrapotherium scraped against each other during life producing sharp tips. Uniquely, the rostrum was much shorter than the mandible. The feet and toes were all small. The narial opening was elevated to the top of the skull. Astrapotherium likely had a tapir-like trunk.

Brachycrus laticeps
(origiginally Merycochoerus Douglass 1900; CM796; Miocene, 14mya; 1m long) was considered an North American oreodont with a tapir-like trunk and deep jaws. Here it nests with South American Astrapotherium. Both are derived from North American Meniscotherium.

Astraponotus assymemetrum
(Ameghiino 1901; Late Eocene 35mya) is a transitional South American taxon between Astropotherium (Fig. 1) and Brachycrus (Figs. 1–3).

We looked at tiny Trigonostylops earlier here. and Meniscotherium earlier here.

Figure 4. Subset of the LRT focusing on Astrapotherium and kin.

This appears to be a novel hypothesis of interrelationships.
If not, please provide a prior citation so I can promote it here.

You probably noticed
the pace of posts has picked up in the last day or two. That’s because it is now Abstracts Season and there is a backlog to get through. That will continue until that drains down a bit. Thank you for your readership, your comments and your continuing interest in paleontology.

References
Ameghino F 1901. Notices préliminaires sur des ongulés nouveaux des terrains crétacés de Patagonie [Preliminary notes on new ungulates from the Cretaceous terrains of Patagonia]. Boletin de la Academia Nacional de Ciencias de Córdoba 16:349-429.
Burmeister 1879. Description physique de al République Agentine, T. III 1879:517.
Douglass E 1900. New species of Merycochoerus in Montana. Part I. American Journal of Science 10(60):428-438.
Hatcher JB 1901. Report of the Princeton University Expeditions to Patagonia 1869-1899. Mammalia of the Santa Cruz Beds. IV. Astrapotheria. Scott WB ed. Vol. 6, Paleontology 3. Princeton, NJ Stuttgart 1909-1928.

wki/Astrapotherium
wiki/Brachycrus
wiki/Astraponotus

A unicorn artiodactyl, Kubanochoerus gigas, enters the LRT

Though pig-like in appearance and temperament,
anthracotheres, deer, camels and giraffes share a last common ancestor in the large reptile tree (LRT, 1978 taxa) a few nodes apart from the pigs (= Suidae) anthraoctheres are often associated with. Pigs and pig-like mammals are more primitive in the Artiodactyla, a clade that does not include hippos or whales in the LRT.

Figure 1. Kubanochoerus skeletal mount. Skull highlighted. Eyeball added.

Kubanochoerus gigas
(Pearson 1928; Miocene; 10mya; 1.2m tall at shoulder) nests with Anthracotherium in the LRT as a large unicorn anthracothere. The horn appears to be (let me know if this is an error) an outgrowth of the mesethmoid, as in the flightless bird, Casuarius. This genus roamed Asia and Europe.

Kubanochoerus skull. Colors added. Noe the wide preaxillary incisors. The maxillary canine is laterally oriented.

Those incisors
are just as impressive as those hippo-like canines. The long rostrum and the extreme brevity of the cranial area are also striking. Somehow I just learned about this genus a few days ago. Why is this not a more popular and widely-known taxon?

You probably noticed
the pace of posts has picked up in the last day or two. That’s because it is now Abstracts Season and now there is a backlog to get through. That will continue until that drains down a bit. Thank you for your readership, your comments and your continuing interest in paleontology.

References
Pearson H S 1928. Chinese fossil Suidae. Paleont Sin, Ser C, 5(5): 1−75.

Dinosaur lecture series on YouTube

Highly recommended, but out-of-date in places
This seems like a freshman course at the University of Maryland. Just a guess…

Even so,
author, lecturer and professor, Thomas R Holtz, Jr, makes it all worthwhile by his enthusiasm. It’s the usual stuff found in popular dinosaur books, but here you’ll be graded and you’ll have to know your ‘oidea’ from your ‘idae’. This first video is recent, posted September 2021 to YouTube. Others posted through October 30 follow.

youtube.com/channel/Thomas_Holtz

Figure 1. Click to play. Frame from Dr. Holtz lecture series on dinosaurs.

Holtz announces
‘No textbook is required for purchase’ in his course. Perhaps that’s a good thing. So take notes! Lots and lots of notes (if you’re a tuition paying student interested in good grades). The artwork on the professor’s slides is first-rate. So is his humor.

So it is with regret that I have to inform readers,
that Professor Holtz follows academic tradition in nesting pterosaurs just outside of dinosaurs (Fig. 2). I can only encourage Dr. Holtz to add taxa to his cladograms to resolve this issue. We’ve know for 20 years that this is wrong.

Figure 1. Slide from professor Holtz’s lecture series is out-dated by twenty years. We’ve know for that long that pterosaurs are not outgroups to dinosaurs. Just look at them! (And click the text links). When I got into paleontology I never thought it would be like this. Logic is absent here as longtime readers know.

Based on Holtz’s own imagery,
pterosaurs are obviously not similar to dinosaurs, yet professors worldwide hold on to this disproved hypothesis. Peer group pressure works at all levels. This is perhaps the most important lesson paleo students need to learn as they leave home and go to university and/or the job market: give your professors what they want to get a good grade, but test everything they say by building your own large cladogram. You’ll get better at it more you do it.

After several videos
long-time readers will notice a slew of other problems. So my enthusiasm for this series is waning.

If and when you get to Holtz’s Triassic video
I commented: Great lecture Thom, but it’s time to get up to date.
Adding taxa:
1. makes Amniota a junior synonym for Reptilia
2. makes ‘Diapsida’ polyphyletic
3. makes ‘Sauropsida’ polyphyletic
4. makes ‘Parareptilia’ polyphyletic
5. nests Eunotosaurus far from turtles and close to other synapsid-mimics like Cotylorhynchus and Milleretta
6. makes Pappochelys a basal placodont, not a ‘proto-turtle’
7. makes Vancleavea a thalattosaur, not an archosauriform
8. makes Archosauria restricted to just dinos + crocs
9. makes ‘Pseudosuchia’ paraphyletic. Use ‘Archosauriformes’ instead.
10. makes the first dichotomy between Archosauromorpha and Lepidosauromorpha (using the original definitions for both). So Archosauromorpha now includes Synapsida (and Mammalia), thus parental care and vocalization goes back much further than just Archosauria, if homologous
11. makes ‘Ornithodira’ a junior synonym for Reptilia since pterosaurs are lepidosaurs and dinosaurs are archorsaurs
12. splits Archosauriformes into Proterosuchus + descendants apart from Euparkeria + descendants
13. makes Dinosauromorpha a junior synonym for Archosauria

Rather than describe clades by traits, it’s always better to avoid convergence and define clades by a last common ancestor based on hundreds of traits and hundreds of taxa.

Rather than choose exemplars like the incomplete Ixaleperton (a protorosaur, not related to pterosaurs) and the incomplete Lagosuchus (a bipedal crocodylomorph, not related to dinosaurs) choose exemplars from completely known and more confidently nested taxa. The freehand drawings you use for both include a healthy dose of artist imagination. As a guide, a cladogram that minimizes taxon exclusion is here: http://reptileevolution.com/reptile-tree.htm

If and when you get to Holtz’s lecture on the origin of flight
I had this to say:
The WAIR films are fantastic, but Thomas, you’re a theropod expert. You should know that gliding never leads to flapping. You should know exactly when theropod/birds took flight and how you can tell in fossils.

Distinct from most dinosaurs with short, round, sliding coracoids, flapping theropod coracoids are elongate and locked to the sternum (=ELS). We find ELS coracoids on pterosaurs and their ancestors back to Cosesaurus. In bats we have ELS clavicles due to a lack of coracoids. Enatiornithes have ELS coracoids. Tianyuraptor does not. Evidence here: https://pterosaurheresies.wordpress.com/2012/03/01/the-locked-down-coracoid-and-the-origin-of-flapping/

That the so-called ‘styliform element’ in Yi qi and Ambiortis is the result of a simple torsion fracture in one ulna of Yi qi and displacement in the other. There’s a longitudinal compressive crack in the left radius of Ambiortis. The right wing is undisturbed and preserves no styliform element. Evidence here: https://pterosaurheresies.wordpress.com/2019/05/09/like-yi-qi-the-new-ambopteryx-does-not-have-bat-wings/

https://pterosaurheresies.wordpress.com/2021/07/04/when-a-simple-torsion-fracture-turned-an-early-cretaceous-bird-into-bizarre-bat-wing-dinosaur/

https://pterosaurheresies.wordpress.com/2015/05/03/no-styliform-element-on-yi-qi-thats-just-a-displaced-radius/

Add more Solnhofen birds to your cladograms to see that no two are alike. Some are basal to Enantiornithes, others to Scansoripterygidae. Jurapteryx and Wellnhoferia lead to Sapeornis, Confuciusornis and extant birds.

Chickens are ducks are not each other’s closest relatives, as any child can tell my looking at their traits, habits and niches. If the genes tell you they are close relatives, then don’t trust genomics in deep time studies. Cladogram here: http://reptileevolution.com/reptile-tree.htm

Pterodactylus scolopaciceps examined under laser

Pittman et al. 2021 brought us a laser-fluorescent look at
Pterodactylus scolopaciceps  BSP 1937 I 18 (Broili 1938, P. kochi No. 21 of Wellnhofer 1970, 1991; Fig. 1). The authors focused on the robust pectoral muscles and the shaping affect that mass had on the leading edge of the torso-to-wing transition zone.

Figure 1. Fluorescent image from Pittaman et al. 2021. White light image from co-author Tom Kaye.

Here we’ll take a closer look at
various other areas exposed on this perfectly preserved, articulated and complete specimen, one we looked at earlier in a four-part series ending here in 2013.

Figure 2. Pterodactylus snout tip. Arrows point to multiple nares anterior to the antorbital fenestra accompanied by nasal (pink) and jugal (cyan) laminated layers.

The lamination of the nasal and jugal
over the maxilla and the persistence of small holes where nares are usually found in Triassic pterosaurs is shown here (Fig. 2). Other workers don’t recognize this because they don’t use look closely at their specimens and they don’t use DGS. This method, used since 2003 (see Jeholopterus in situ in the masthead above), simplifies and clarifies one bone from another better than simple line art tracings.

Figure 3. Pterodactylus cranium. Here the squamosal (magenta) is split due to taphonomy. On most pterosaurs the quadrate is vertical to posterior leaning. Here the quadrate is prone = horizontal. Palate bones are not colored here.

Despite the promise of laser fluorescence
white light can still provide details missing from other wave lengths (Fig. 3). Sometimes a closer look, a little Photoshop and a reconstruction (Fig. 12) bring more understanding for scoring traits.

Figure 4. Pterodactylus torso and tail.

Whenever ribs and gastralia are involved
it is best to segregate them by color (Fig. 4) in order to understand the situation with more clarity. Then the colors can be copied and pasted to make a reconstruction (Fig. 12). Note the wider than expected shape of the rib cage + gastralia, creating its own disc-like lifting surface, as in Eudimorphodon and Sharovipteryx. This shape has not been noticed by workers or paleo artists previously, who keep giving Pterodactylus a traditional tubular fuselage (= torso).

Figure 5. Pterodactylus right manus. The fingers are displaced from the metacarpals.

The orientation of the three free fingers in pterosaurs
has vexed workers, like Chris Bennett, and paleoartists who follow his reconstructions. Here (Fig. 5) the disarticulated fingers lay flat because they are crushed like the rest of the skeleton. Ten years ago a post here presented both hypotheses. In life, pterosaur fingers fllexed ventrally, as in all other tetrapods, not anteriorly and stacked as Bennett imagined and others followed.

Figure 6. Pterodactylus right wrist.

The right wrist of Pterodactylus
(Fig. 6) is slightly disarticulated. Coloring the elements by hand brings more clarity than any other method.

Figure 7. Pterodactylus left wrist.

The left wrist of Pterodactylus
(Fig. 7) likewise brings more clarity when hand colored. Vestigial digit 5 is undisturbed here on the now dorsal (due to axial rotation) of the big metacarpal 4 that supports the wing finger.

Figure 8. Pterodactylus right elbow. Note the wing is stretched only between the elbow and wing tip, as in all other pterosaurs. No exceptions.

The right elbow of Pterodactylus
(Fig. 8) clearly shows the narrow chord wing membrane aft of the elbow, contra most depictions of pterosaurs in which the artist gives the pterosaur a bat-like membrane. Embarrassing for all of us who love pterosaurs that this myth continues over a century after it was first corrected by Zittel 1882 and more recently in Peters 2002.

Figure 9. Pterodactylus tail, right foot and uropatagium.

The knee, foot and tail of Pterodactylus
(Fig. 9) were detailed and reconstructed previously (Fig. 12). Note the rather limited extent of the uropatagium with no contact whatsoever with pedal digit 5. So, pterosaur artists, stop mucking about trying to put a connection there. The purported uropatagium in Sordes (Unwin and Bakhurina 1994) is a displaced wing, as shown here, as explained in Peters 1995 and ignored ever since.

Figure 10. Pterodactylus tarsus and pedal digit 5. Not the large ungual on this vestigial toe.

A closer view of the Pterodactylus ankle
(Fig. 10) shows the always overlooked vestigial ungual on digit 5. Also note the cylindrical proximal tarsal elements. This shape enables hyperextension of the foot during flight.

Figure 11. This is Figure 1B of Martin-Silverstone et al. 2020 where they mislabel the left and right wings, but correctly labeled the muscles (m) featured in Pittman et al. 2021. Colors added to show the extent of the wing membrane.

As mentioned earlier,
this perfect Pterodactylus specimen was looked at by Martin-Silverstone et al. 2020 (Fig. 11) in white light. This is a popular specimen to write papers about.

Figure 12. Pterodactylus scolopaciceps reconstructed. Note the wide umbrella-like ribcage and gastralia, as in Jeholopterus. Such a wide ribcage keeps this lepidosaur’s elbows and knees in a sprawling posture.

Figure 13. Click to animate. Plantigrade and quadrupedal Pterodactylus walk matched to tracks. More bird-like than bat-like, this pterosaur was balanced over its toes, able to launch bipedally at a moment’s notice by extending its wings and leaping like a typical bird.

Figure 14. Another Pterodactylus specimen, NHMW 1975/1756, animated to show wing and leg extension with membranes as they are in the fossil, not as artists influenced by the mistakes of Unwin and Bakhurina 1994 imagine them.

The new data provided by Pittman et al. 2021
has been added to the reconstruction in ReptileEvolution.com (Fig. 12), an ongoing online study that is constantly making additions, adjustments and corrections because that makes for good science. And it keeps me busy in my retirement.

References
Martin-Silverstone E, Habib MB and Hone DWE 2020. Volant fossil vertebrates: Potential for bio(-)inspired flight technology. Trends in Ecology & Evolution (advance online publication) doi: https://doi.org/10.1016/j.tree.2020.03.005
Peters D 1995. Wing shape in pterosaurs. Nature 374, 315-316.
Peters D 2002. A New Model for the Evolution of the Pterosaur Wing – with a twist. – Historical Biology 15: 277–301.
Pittman M, Barlow LA, Kaye TG and Habib MB 2021. Pterosaurs evolved a muscular wing–body junction providing multifaceted flight performance benefits: Advanced aerodynamic smoothing, sophisticated wing root control, and wing force generation. PNAS 118(44): e2107631118
Unwin DM and Bakhurina NN 1994. Sordes pilosus and the nature of the pterosaur flight apparatus. Nature 371: 62-64.
Zittel KA 1882. Über Flugsaurier aus dem lithographischen Schiefer Bayerns. Palaeontographica 29: 7-80.

Thanks to co-author Tom Kaye for providing a high-resolution white-light image.

https://pterosaurheresies.wordpress.com/2013/03/01/a-perfect-pterosaur-pterodactylus-scolopaciceps-n21-part-1/

https://pterosaurheresies.wordpress.com/2013/03/02/a-perfect-pterosaur-pterodactylus-scolopaciceps-n21-part-2/

https://pterosaurheresies.wordpress.com/2013/03/03/a-perfect-pterosaur-pterodactylus-scolopaciceps-n21-part-3/

https://pterosaurheresies.wordpress.com/2013/03/04/a-perfect-pterosaur-pterodactylus-scolopaciceps-n21-part-4/

Enigmatic Niobrara fish, Martinichthys, enters the LRT with extant Arapaima

Martinichthys brevis (McClung 1926; Taverne 1999; KUVP 497; Late Cretaceous; Fig. 1) is a rare Niobrara fish here nesting with the slow-moving, extant, Amazon giant, Arapaima (Figs. 2, 3). Taverne 1999 considered this fish in the same clade as the distinctly different Pentanogmius.

Figure 1. Two species assigned to the genus Martinichthys from the Niobrara. Colors and some restoration added here. Compare to previously overlooked Arapaima in figures 2 and 3. Scale bars are cm.

Not sure why Arapaima was overlooked in prior studies.
This may be so because adding living taxa to fossil cladograms does not happen very often. The large reptile tree (LRT, 1978 taxa) minimizes taxon exclusion by adding taxa, both extinct and extant, in order to minimize taxon exclusion.

Figure 2. Skull of Arapaima in two views. Compare to Martinichthys in figure 1.

The post-crania of Martinichthys
is not known except for a few vertebrae. Workers believe this may be due to poor ossification. Based on the similar size and morphology of the Arapaima skull, Martinichthys was likely about the same size and shape (Fig. 3).

Figure 3. Amia, Arapaima and several related taxa in the LRT to scale and to a common snout-tail length compared to the largest taxon in this graphic, Arapaima.

Once again, this appears to be a novel hypothesis of interrelationships.
If not, please provide a prior citation so I can promote it here.

References
McClung CE 1926. Martinichthys, a new genus of Cretaceous fish from Kansas, with descriptions of six new species. Proc. Amer. Philos. Soc. 65 no. 5, (suppl.) 20-26, 2 pls.
Taverne L 1999. Révision du genre Martinichthys, poisson marin (Teleostei, Tselfatiirormes) du Crétecé supérior du Kansas (États-Unis). Revision of the genus Martinichthys, marine fish (Teleostei, Tselfatiiformes) from the Late Cretaceous of Kansas (United States) Geobios 33(2):211-222.

oceans_of_kansas_martinichthys
wiki/Arapaima
wiki/Martinichthys
wiki/Tselfatiiformes

Enigma Yalkaparidon nests in the LRT with other marsupial enigmas

Popularly known as ‘Thingodonta‘,
the small partial skull of Yalkaparidon coheni (Archer, Hand and Godthelp 1988; Early Miocene; QM-F13008; Fig. 1) is a traditional enigma marsupial. According to the Australian Museum, “nobody knows what its closest relatives are.”

This sounds like a job for the LRT! Thirty-three years of enigma-hood is far too long.

Figure 1. Yalkaparidon skull (right view flipped, colors and animation added). Shown about 1.5x actual size on a 72dpi computer monitor. Note how the anterior jugal has a descending process, taken to an extreme in Vintana in figure 2.

Here
in the large reptile tree (LRT, 1974 taxa; subset Fig. 4), Yalkaparidon nests basal to two other traditional enigma marsupials, Vintana (Fig. 2) and Groberia. Academic workers consider Yalkaparidon a diprodontian. Here Yalkaparidon is a diprodontian-mimic, not related to Diprodonton. These three taxa are close to Paedotherium and another rather new enigma, Adalatherium.

The reasons for the traditional omission of these taxa from marsupial trees:
Paedotherium was traditionally considered a notoungulate, a placental. It is neither in the LRT. Paedotherium was nested with marsupials here in 2019. Worse yet, Notoungulata is no longer a monophyletic clade after testing in the LRT.

Figure 2. Vintana as originally illustrated. I added colors to certain bones. Note the high angle of the ventral maxilla and the deep premaxilla. Lateral view reduced to scale with other views.

Archer et al. 1988
erected a new order for Yalkaparidon (Fig. 1). Adalatherium, Groberia and Vintana were described later as unique taxa, so they might have nested in this order. Unfortunately papers describing each new ‘unique’ taxon did not mention Yalkaparidon or Archer.

Described in 1888, Paedotherium
has traditionally and mistakenly considered a member of the Notoungulata and the Eutheria. Neither are correct according to the LRT. According to the LRT, Notoungulata is a wastebasket clade and is not monophyletic. Eutheria include placental mammals. Papers describing each new ‘unique’ taxon (Yalkaparidon (Fig. 1). Adalatherium, Groberia and Vintana) did not mention Paedotherium (Fig. 3).

Figure 3. Miocene Paedotherium was excluded by Krause et al. It nests with Late Cretaceous Adalatherium in the LRT.

Beck et al. 2013 ran a cherry-picked analysis
that omitted pertinent taxa listed above. They reported, “characters are similarly poorly resolved and do not clarify the supraordinal relationships of Yalkaparidon beyond suggesting that it is probably a member of Marsupialia.” They concluded, “We have not been able to confidently resolve the phylogenetic relationships of this taxon.”

Convergence can be troublesome.
Let the software determine your inclusion set, outgroups and all interrelationships. Don’t short-change your study by cherry-picking taxa. The more taxa, the better. The LRT minimizes taxon exclusion by including so many taxa, more than in any other similar study.

Figure 4. Subset of the LRT focusing on basal Theria = Marsupialia.

Whatever they teach you at the university level,
it is not necessary to personally examine a specimen like this firsthand in order to understand it better than those who examined it firsthand. It is also not necessary to add characters for tiny cranial foramina and other minutia. Beck et al. proved that. Instead, it is only necessary to include related and pertinent taxa in a single analysis. If you don’t know which taxa are related and pertinent, just keep adding taxa until your software tells you which taxa are related and pertinent. Don’t assume anything you learned under the tutelage of a professor. Sometimes they know. Sometimes they don’t. Test every taxon you can get your eyes on in one large study. Then, when you have your own large cladogram, like the LRT, you can use it with authority for the rest of your career.

Once again, this appears to be a novel hypothesis of interrelationships.
If not, please provide a citation for the earlier hypothesis so I can promote it here.

PS
This reminds me of the origin of pterosaurs problem from twenty years ago. Back then, adding taxa nested enigma pterosaurs with enigma Cosesaurus, with enigma Sharovipteryx and with enigma Longisquama.

Lesson for today (and twenty years ago):
Add taxa and your enigmas will get nested. Don’t expect any celebration, acknowledgement or approbation, but that’s how you do it. Just add taxa.

References
Archer M, Hand S and Godthelp H 1988. A new order of Tertiary zalambdodont marsupials. Science 239(4847):1528-1531.
Beck RMD 2013. The osteology and systematics of the enigmatic Australian Oligo-Miocene metatherian Yalkaparidon (Yalkaparidontidae; Yalkaparidontia; ?Australidelphia; Marsupialia). J Mammal Evol DOI 10.1007/s10914-013-9236-3

wiki/Vintana
wiki/Paedotherium – not yet listed, let’s fix that!
wiki/Groeberia
wiki/Adalatherium
wiki/Yalkaparidon

Publicity
Australian.museum/learn/australia-over-time/extinct-animals/cohens-thingodonta/

Washingtonpost.com/news/speaking-of-science/wp/2016/05/27/this-odd-ancient-australian-marsupial-had-an-insatiable-appetite-for-snails/

Barbourofelis enters the LRT as a sabertoothed marsupial, not a big cat

Not sure how this mistake was overlooked for fifty years.
But other traditional mistakes have survived and thrived far longer. C’est la vie paleo!

Barbourofelis fricki (Schultz, Schultz and Martin 1970; Middle to Late Miocene, 13-7mya) was traditionally considered a placental member of the Carnivora and a big cat (= Feliformia). Here it nests with Thylacosmilus (Fig. 2) as a saber-toothed marsupial. Distinct from Thylacosmilus, four procumbent tooth alveoli are present on a broad, transverse premaxilla. Three large molars have shearing surfaces, as in big cats, rather than typical grinding surfaces. The premolars are tiny. The sabers are slender, as in Thylacosmilus. The orbit is enclosed, as in Thylacosmilus. The dentary has saber flanges (not scored in the LRT), as in Thylacosmilus. The mandible (= dentary) must hyper extend in order to clear the sabers.

Figure 1. Barbouorfelis fricki from Schultz, Schultz and Martin 1970. Colors and animation added here. Compare to Thylacosmilus in figure 2.

Marsupial relatives of Thylacosmilus and Barbourofelis include
Vincelestes from the Early Cretaceous, which also has large, semi-saber canines, both uppers and lowers. So saber-toothed therians held their own against dinosaur predators throughout the Cretaceous. This gave plenty of time for Thylacosmilus and Barbourofelis to diverge in traits and geography, yet so much remained the same.

Figure 2. Thylacosmilus skull. Colors added here. The premaxilla is unknown here. The maxillae are inflated dorsally to contain the canine roots. Compare to Barbourofelis in figure 1.

Moving Barbourofelis to Panthera
(the placental, Carnivora, Feliformia, lion) in the large reptile tree (1973+ taxa) adds 32 steps.

According to Wikipedia/Thylacosmilidae,
“The family’s most notable feature are the elongated, laterally flattened fangs, which is a remarkable evolutionary convergence with other saber-toothed mammals like Barbourofelis and Smilodon.”

By contrast, the LRT nests Barbourofelis with Thylacosmilus. Smilodon came along later by convergence.

Figure 3. Subset of the LRT focusing on basal Theria = Marsupialia.

This appears to be a novel hypothesis of interrelationships.
If not, please provide a citation so I can promote it here.

References
Schultz CB, Schultz MR and Martin LD 1970. A New Tribe of Saber-toothed Cats (Barbourofelini) from the Pliocene of North America. Bulletin of the University of Nebraska State Museum. 9 (1).

wiki/Thylacosmilus
wiki/Schowalteria
wiki/Barbourofelis
wiki/Barbourofelidae
wiki/Thylacosmilidae

Enigmatic Apterodon enters the LRT with marsupial dogs and cats

Updated April 2, 2022
with nearly a hundred more taxa and scoring corrections.

Taxon exclusion problems have followed this genus
for over 100 years. In the large reptile tree (LRT, 1972+ taxa; subset Fig. 4) Apterodon (Fig. 1) nests with the IVPP V 12385 specimen assigned tentatively to Hapalodectes hetangensis (Fig. 2). Apterodon is much larger and the orbit is further forward. It is best known from two 20cm skulls (AMNH 13236 and 13237) and a mandible (AMNH 13241, Fig. 3) from Oligocene deposits in the Fayum Depression of Egypt where small to giant archaeocete whales are found. The related tiny anagalid, Ptolemaia, is also found there.

According to Wikipedia
“Apterodon is an extinct genus of hyaenodontid mammal that lived from the mid Eocene through the Oligocene epoch.”

Perhaps they were following Szalay 1967, who reported, “As is shown in the above presentation and discussion, the undoubted hyaenodontid affinity of Apterodon is confirmed.” In the LRT (Fig 1) Hyaenodon nests in a nearby clade.

Figure 1. Apterodon, Pterodon, Hapalodectes and kin derived from a sister to Thylacinus. Note the convergence here with placental dogs and cats.

Szalay and all prior workers were slightly wrong, according to the LRT.
Taxon exclusion is the issue here (again). Hyaenodontids are creodont marsupials in the LRT. Szalay followed Van Valen 1965 who erected the clade Deltaheridia within Creodonta within Placentalia, separating these clades from Carnivora, not realizing the marsupial affinities.

Figure 3. Apterodon skull and mandible material. The AMNH 13237 small skull (lateral view) is the same one shown in figure 1 as a diagram.

Szalay 1967 wrote,
“The mere fact that the preglenoid process of Apterodon is large and well developed (point 3) is a feature shared with mesonychids. Instead of viewing one fact out of context, however, we can examine the structures that are in close morphogenetic dependence on one another-in
this case the entire zygomatic portion of the squamosal and its relation to the posterior part of the cranium.”

Ironically,
Szalay 1967 was the first worker to warn others not to “Pull a Larry Martin” when he said, “Instead of viewing one fact out of context”. Then he went ahead and pulled his own Larry Martin when he continued, “however, we can examine… the entire zygomatic portion of the squamosal and its relation to the posterior part of the cranium.”

Don’t list traits. Run your analysis. Let the software do the work. Find a last common ancestor for your clade of interest. Then list traits, noting instances of convergence. Granted, no one in 1967 had this option.

Van Valen 1966 wrote:
“The relationships of Apterodon are questionable.” He mentions that several workers considered Apterodon a mesonychid, then lists several hyaenodontid traits found in Apterodon that are not known in mesonychids, then reverses himself with other traits.

Van Valen 1966 also wrote,
“Ptolemaia has a number of similarities to the Mongolian genus Anagale, of which the most important follow.” In the LRT (Fig. 4) Ptolemaia (also from the Fayum Depressions) is another sister to Apterodon, but Van Valen never made the connection.

According to Wikipedia
“With the exception of the type species, A. gaudryi, all species of Apterodon are known from Africa. Uniquely among hyaenodontids, it was a semiaquatic, fossorial mammal. It possessed strong forelimbs that were well equipped for digging, compared to those of modern badgers, while the tail, torso and hindlimbs show adaptations similar to those of other aquatic mammals like otters and pinnipeds. The dentition was suited to feed on hard-shelled invertebrate prey, such as crustaceans and shellfish. It probably lived along African coastlines.”

Previous workers did not include Apterodon sister taxa in their analyses.
Omitting taxa leads to confusion. The LRT leads to discovery by minimizing taxon exclusion. Other workers minimize discovery by omitting taxa. Don’t follow those who are academically forced to do the bidding of their professorial masters. Don’t follow those who borrow cladograms or create supertrees. Create your own cladogram. Then you’ll have this powerful tool for the rest of your professional career.

Apterodon macrognathus
(Fischer 1880; Eocene to Oligocene; Fig. 1) was considered a member of the Hyaeodontida, a clade within Creodonta, a clade within Marsupialia in the LRT. Here Apterodon nests with the IVPP V 12385 specimen (Fig. 2) assigned tentatively to Hapalodectes hetangensis (above) close to the Delatheroidea. Apterodon is much larger, The orbit is further forward. The teeth extend behind the orbit. What looks like a carnassial is the anterior of four molars. The small, transverse premaxilla has two robust teeth. The mandible (= dentary) has no retroarticular process in one species, a straight process in another. Most specimens are from Egypt. The type genus is from Germany.

This appears to be a novel hypothesis of interrelationships.
If not, please provide a citation for the earlier hypothesis so I can promote it here.

wiki/Apterodon

Marsupials, Monotremes and Cynodonts in the Mesozoic

Today’s post
follows on the heels of yesterday’s post on Mesozoic placentals. Here (Fig. 1) are the current Mesozoic marsupials, monotremes and cynodonts tested in the large reptile tree (LRT, 1970+ taxa). Apparently we know of many more Mesozoic pre-placentals than Mesozoic placentals. Here the known geographic ranges are also indicated.

Figure 1. Subset of the LRT focusing on Mesozoic cynodonts, monotremes and marsupials and their known geographic distribution.

Basically,
the Early Permian synapsids are known from North America and the Late Permian to Triassic and Jurassic therapsids and basal mammals are known from Old World continental areas despite the presence of a single continent, Pangaea, during these times. Geographic exceptions are notable and important.

Herbivorous marsupials of the Cretaceous
are known chiefly from Australia, South America and Madagascar, all part of Gondwana at the time.

Carnivorous marsupials of the Cretaceous,
from Early Cretaceous Vincelestes to Late Cretaceous creodonts and were more worldwide in distribution.

Figure 2. Monodelphis mother with her growing brood of young clinging to her fur and nipples. This is why we should all celebrate Mother’s Day every day.

Neither of these specialist marsupials contributed to the lineage of Placentalia
which arose from basal omnivores: the didelphids (= opossums), like the extant Virginia opossum (Didelphis), and the much smaller, also extant, gray short-tailed opossum from South America (Monodelphis, Fig. 2). The latter has prepubic bones, but lacks a pouch. According to the LRT, both of these living fossil taxa must have had their genesis in the Early Jurassic.

On their own, large cladograms can be daunting.
However, when given a few pertinent graphic colors, phylogenetic patterns can appear to help simplify the underlying distribution of taxa both in time and place.

Placentals in the Mesozoic? Clues from continental drift.

According to Wikipedia:
“True placentals may have originated in the Late Cretaceous around 90 MYA, but the earliest undisputed fossils are from the early Paleocene, 66 MYA, following the Cretaceous–Paleogene extinction event.” Unfortunately, Wikipedia also follows the results of genomic testing which nest armadillos and elephants at basal nodes and nest bats with horses at more derived nodes.

If you’re puzzled right now
how scientists can present such untenable results, :- ) you have common sense.

By contrast,
trait testing in the large reptile tree (LRT, 1970 taxa; Fig. 2) nests small, tree shrew-like marsupials without pouches, like Monodelphis, basal to small, tree shrew-like placentals, like Tupaia, Ptilocercus and Nasua.

Today’s topic:
Did the Mesozoic include just a few placentals? Or none?
If a few, are there many more Mesozoic placentals waiting to be discovered?

Plate tectonics may hold some answers.
We can ask, ‘which primitive placental sister taxa appear on opposite sides of the widening Atlantic Ocean after its appearance in the Early Cretaceous (Fig. 1)?’

We can overlook those derived Eocene placentals
that crossed the Bering Strait during the Paleocene Eocene Thermal Maximum (e.g. North American adapids (lemurs) > South American monkeys, Fig. 3).

We can also overlook those derived Ice Age placentals
(e.g. Mammuthus) that also crossed the Bering Strait.

Here we’ll concentrate on Mesozoic placentals
and, to a lesser extent, Paleocene fauna (Fig. 2).

Backstory
1. Earlier we looked at the splitting of North American taxa, like Procyon (= raccoons) and Mephistis (= skunk), from African taxa, like Suricata (= meerkats) and several mongooses (Herpestes and Cryptoprocta) prior to the Early Cretaceous appearance of the Atlantic Ocean 115mya (Fig. 1).

Figure 1. The Earth at 125, 100 and 66 million years ago showing the splitting of the continents and creation of the Atlantic Ocean. Here sister taxa, raccoons (Procyon) and meerkats (Suricata) appear today on opposite sides of the Atlantic. So their last common ancestor must have appeared before the appearance of the Atlantic that separates them now.

More backstory
2. Earlier we also looked at a novel nesting of Jurassic Multituberculata (e.g. Shenshou) with other gnawing taxa, like Mus (= mouse) and Rattus (= rat). That means basal taxa preceding multis in the LRT must have preceded multis in the Jurassic. Examples include Jurassic Henkelotherium (a pre-rabbit) and Maiopatagium (a pre-porcupine). Unfortunately prior mammal workers nested rodent-like multis around dissimilar monotremes due to jaw and ear reversals because these workers omitted rodents from analysis. That’s why Wikipedia cannot tell you if there were placentals in the Mesozoic. By contrast, the LRT (subset Fig. 2) minimizes taxon questions like this by minimizing taxon exclusion.

Figure 2. Subset of the LRT focusing on placental taxa. Note: some taxa are more or less universally distributed across the globe. These are shown as half and third colors. Note the appearance of only a few Mesozoic placentals and the phylogenetic clues they give to more Mesozoic placentals waiting to be discovered.

As we start this discussion keep in mind that mammal fossils are rare.
Given this parameter, if a fossil genus is found only in Europe, Africa or Asia (at present), a sister taxon might someday be found in North America. Or not. It’s still early and all results are not in.

At the base of the clade Placentalia
Example 1. the extant civet (Nandinia) is known from Africa. It’s extant sister, the coatimundi (Nasua) is known from North America. These two very primitive taxa likely spread worldwide prior to the Early Cretaceous appearance of the Atlantic.

Near the base of the clade Placentalia
Example 2. Tree shrews (Ptilocercus), colugos (Cynocephalus) and pangolins (Manis) along with their earliest known relatives are restricted to the Old World. Their sister taxa, Early Eocene, Chriacus and Eocene basal bats, are known from the New World. That split likely preceded the opening of the Atlantic. Middle Eocene bats in Europe had either migrated over the warm Bering Strait (Fig. 3) or all these taxa were worldwide in distribution prior to the opening of the Atlantic Ocean. Time (and more fossils) will tell.

Figure 3. The North Pole during the earliest Eocene from the CR Scotese Paleomap project with early primate skulls added, each demonstrating a gradual accumulation of traits.

At the base of the clade Glires
Example 3. Extant Solenodon is known only from the Caribbean. A Late Cretaceous sister, Zalambdalestes, is from Mongolia. These two primitive taxa likely radaited worldwide prior to the appearance of the Atlantic based on them phylogenetically preceding Late Jurassic taxa. These would be part of the traditional small mammal assemblage that tried to avoid predatory dinosaurs during the day by only coming out at night, out of sight.

Finally, let’s compare small basal taxa with large derived taxa
First, note the small, arboreal omnivores and carnivores at the top third of the LRT (Fig. 2) and their worldwide distribution.
Second, note the small, arboreal herbivores at the middle third of the LRT are chiefly from the Old World, but exceptions indicate many were worldwide in distribution. Both of these are Mesozoic in origin.
Third, note the majority of larger, terrestrial herbivores (e.g. Onychodectes, Ectoconus) at the bottom third of the LRT are known chiefly from New World taxa. So far, all these are Paleocene (post dinosaur) in their first appearance.

So, is this size pattern real?
Or is it an artifact of strata and discovery? It’s still early and all results are not in.

Once again,
if you add color to taxa (this time in cladograms), surprising patterns can emerge. These ‘patterns’ might be random. Then again, someday (maybe today!) these patterns might be trying to tell us something.

Lesson for today:
Don’t be content with black and white cladograms.

References
wiki/Placentalia