Trigonostylops: a basal astrapothere in the LRT

The premaxilla,
nasal and anterior maxilla are missing in Trigonostylops (Fig. 1). Nevertheless this taxon nests between Meniscotherium and Brachycurus, basal to astrapotheres in the large reptile tree (LRT, 1970+ taxa; Fig. 3).

Simpson 1933 imagined
a possible cat-like rostrum due to missing facial bones (Fig. 1).

Figure 1. Trigonostylops skull (AMNH VP-28700) in several views. Diagram is from Simpson 1933..

MacPhee et al. 2021
labeled Trigonostylops an ungulate. They wrote, “In 1933 George G. Simpson described a remarkably complete skull of Trigonostylops, an Eocene South American native ungulate (SANU) whose relationships were, in his mind, quite uncertain. Although some authorities, such as Florentino Ameghino and William B. Scott, thought that a case could be made for regarding Trigonostylops as an astrapothere, Simpson took a different position, emphasizing what would now be regarded as autapomorphies. He pointed out a number of features of the skull of Trigonostylops that he thought were not represented in other major clades of SANUs,
and regarded these as evidence of its phyletic uniqueness.”

Phyletic uniqueness’ is an oxymoron. Phylogenies, by definition, are based on similarities and relationships. In any case, Trigonostylops is not close to ungulates in the LRT. MacPhee et al 2021 omitted too many pertinent taxa and added unrelated marsupials they thought were related because vertebrate paleontology textbooks said so and other workers imagined so.

“Simpson’s classification was not favored by most later authors, and in recent decades trigonostylopids have been almost universally assigned to Astrapotheria.”

In LRT Trigonostylops also nests with Astrapotherium and kin, confirming earlier workers.

“Overall, we found that this new assessment strengthened the placement of Trigonostylops within a monophyletic group that includes Astrapotherium and Astraponotus, to the exclusion of other SANU clades.” SANU = South American Native Ungulate = misnomer

Figure 2. Astrapotherium to scale with the smaller Brachycurus and transitional Astraponotus.

taxon exclusion marred the phylogenetic analysis of MacPhee et al. 2021. The authors mistakenly included several marsupials they thought were notoungulate placentals, but to their credit, they did nest Trigonostylops with Astraponutus and Astrapotherium (Fig. 2). The only resolution in their cladogram was in the unrelated perissodactyls (3 taxa), liptoterns (4 taxa) and the marsupials they believed were members of the Notoungulata, an invalid clade in the LRT due to the polyphyly of its traditional membership.

Figure 3. Subset of the LRT focusing on astrapotheres and kin.

Adding taxa solves most problems like this.
You can study your favorite taxon until exhaustion, but then you’re only halfway there. Every focused study needs to be combined with a wider view of related taxa. Pterosaur workers don’t get this simple concept. Neither do whale, turtle, shark, placoderm, archosaur, lepidosaur, archosauriform and dinosaur workers. Be the first paleontologist you know to cover all the bases. Grow your own cladogram. Don’t borrow one.

Ameghino F 1897. Les mamiferes crétacés de l´Argentine. Boletín Instituto Geográfico Argentino:18: 405–521.
MacPhee RDW, et al. (5 co-authors) 2021. Cranial Morphology and Phylogenetic Relationships of Trigonostylops wortmani, an Eocene South American Native Ungulate. Bulletin of the American Museum of Natural History 449(1), 1-183.
Simpson GG 1933. Structure and affinities of Trigonostylops. American Museum Novitates 608: 1–28.


Updating Arsinoitherium, Uintatherium and Periptychus

Three years ago
Shelley, Williamson and Brusatte 2018 took a detailed look at every bone known from the North American Paleocene ‘condylarth’ Periptychus canrinidens (Fig. 1).

they were unable to link Periptychus to other taxa. Their first problem was taxon exclusion. If they had not excluded taxa, they might have not mislabeled several skull bones (Fig. 1), their second problem.

Figure 1. Skull of Periptychus in three views from Shelley et al. 2018. Colors added here. The lacrimal and nasal traits are unique to this clade.
Figure 1. Skull of Periptychus in three views from Shelley et al. 2018. Colors added here. What Shelley et al. labeled a mx (maxilla) is actually the lacrimal sometimes called the septomaxilla when it extends toward the naris. Here the maxilla does not overlap the lacrimal as it does in Uintatherium (Fig. 2) where it becomes a hollow, air-filled horn.

Back then,
with 700 fewer taxa, the LRT nested hornless Periptychus carinidens with several multi-horned taxa, including the famous and traditionally enigmatic, Uintatherium (Fig. 2) and Arsinoitherium (Fig. 3).

Figure 2. Uintatherium skull with bones colored and labeled. Note the double appearance of the lacrimal. The anterior portion is often called the septomaxilla, but here appears as a horn. Compare to figures 1 and 3.

From the Shelley et al. abstract:
“We comprehensively describe the cranial, dental and postcranial anatomy of Periptychus carinidens based on new fossil material from the early Paleocene (Torrejonian) of New Mexico, USA. The cranial anatomy of Periptychus is broadly concurrent with the inferred plesiomorphic eutherian condition, albeit more robust in overall construction. The anatomy of Periptychus
is unique and lacks any extant analogue; it combines a basic early placental body plan with numerous unique specializations in its dental, cranial and postcranial anatomy.”

No extant analog exists,
but several extinct homologs (Figs. 2-4) should not be overlooked.

Figure 3. Arsinoitherium, colors added here. Note the large hollow horns are created by the septomaxilla (= lacrimal). The small horns arise from the frontals. These are among the few mammals in which the premaxillary ascending process reappears.

Shelley et al. vaguely compared Periptychus to
a short list of cherry-picked taxa, but did not run a wide-gamut phylogenetic analysis. So they were trying to “Pull a Larry Martin“, hoping to find some comparable traits. Don’t do that. Run an analysis. Shelley et al. did not compare Periptychus to Gobiatherium, Uinatatherium and Arsinoitherium.

Figure 4. Gobiatherium, another related taxa with a premaxillary ascending process and a septomaxilla contributing strongly to a nasal crest.

Rather than search for homologous traits with cherry-picked taxa,
just keep adding pertinent taxa to your cladogram. Let your software recover a cladogram that will tell you which taxa are closest to your enigma taxon. Then you can study and discuss the various homologies that will be well supported by your own valid phylogenetic analysis.

Cope ED 1881.
The Condylarthra (Continued). American Naturalist 84;18: 892–906.
Shelley SL, Williamson TE and Brusatte SL 2018. The osteology of Periptychus carinidens: A robust, ungulate-like placental mammal (Mammalia: Periptychidae) from the Paleocene of North America. PLoS ONE 13(7): e0200132.

Patriofelis YouTube video presentation by Paleo Talks [58]

This is an excellent look
at what paleo writer Riley Black, considers an enigma taxon. It is not an enigma in the LRT.

My comments on the video
“Always good to hear Riley Black, a well-respected and prolific paleojournalist who digs deep into our favorite subject. Testing all competing and several overlooked kinship candidates nests Patriofelis as a cougar-sized honey badger (Mellivora). Kerberos is a smaller more primitive relative. Sarkastodon is much larger. To Black’s best guesses, this clade nests between otters + wolverines and sea lions + hesperocyonids using trait analysis (not genes) here: That cladogram also nests enigmatic Uintatherium with Coryphodon and these with Arsinoitherium and hornless more primitive Periptychius, all phenacodontids (no living relatives).

PS Creodonts are all marsupials.

PPS The ‘oddball’ Stylinodon mentioned late in the video nests between bears and seals, arising from primitive clade members Machaeroides and Ectoganus, close to Amphicynodon + Psittacotherium.”

Figure 4. Patriofelis museum mount. This is the sort of wolverine (genus: Gulo) that evolves into seals and walruses.
Figure 1. Patriofelis museum mount. This is an extinct honey badger.
Figure 3. Patriofelis skull in two views.
Figure 2. Patriofelis skull in two views.

Patriofelis ulta
(Leidy 1873; Middle Eocene; 1.5m snout to vent length) was a large, extinct honey badger the size of a cougar, but with shorter legs and wider feet.

Figure 2. The honey badger (Mellivora capensis) skeleton.
Figure 3. The honey badger (Mellivora capensis) skeleton.

Leidy J 1873. Contributions to the extinct vertebrate fauna of the Western Territories,
Rep. US Geol. Surv. Terr. (Hayden), vol. 1, pt. 1, pp. 7-358 (114-116, 316), pis. 1-37.

wiki/Honey_badger – Melivora
wiki/Kerberos – not yet posted in wiki

Dissacus: transitional between oreodonts and mesonychids

This post follows in the wake of a series of recent updates
as Dissacus is moved back closer to mesonychids, where it was originally nested. Dissacus now nests transitional between oreodonts and mesonychids in the large reptile tree (LRT, 1968+ taxa; subset Fig. 4).

Figure 1. Dissacus zanabazari from Geisler and McKenna 2007. Colors and restoration added here.

Geisler and McKenna 2007
described the partial remains of Dissacus zanabazari (MAE−BU−97−13786; Fig. 1) from Mongolia. They considered Dissacus to be a mesonychid after phylogenetic analysis.

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 related oreodonts or basal terrestrial herbivorous placentals, like Phenacodus, or any hippos were tested by Geisler and McKenna 2007. Even so, getting close is sometimes good enough, especially in phylogenetic analysis.

Figure 2. Ocepeia nests with oreodonts in the LRT.

Primitive oreodonts preceded the creation of the Atlantic Ocean
The LRT now nests Middle Paleocene, North African Ocepeia with Merycoidodon (Figs. 3a, 3b), within Oreodonta (= Merycoidodonta), a clade previously known only from Eocene to Miocene North America. Gheerbrant et al. 2014 reported, “a remarkable mosaic of primitive eutherian-like, insectivore-like, ungulate-like, and autapomorphic features. The trees recover a sistergroup relationship of Perissodactyla and Paenungulata, mostly based on the shared bilophodonty, which challenges monophyly of Afrotheria and afrotherian relationships of Ocepeia.”

Figure 3a. Merycoidodon reconstruction traced by an unknown artist from an AMNH mount photo, and Ocepeia to scale.
Figure 2. Merycoidodon skull. Colors added.
Figure 3b. Merycoidodon skull. Colors added.

Perhaps it was “remarkable” due to taxon exclusion. Gheerbrant et al. 2014 cherry-picked several suprageneric taxa (= bad idea), several generic taxa and no oreodonts, mesonychids or hippos. The authors also accepted the genomic clade, Afrotheria (= invalid hypothesis of interrelationships), which vertebrate paleontologists still accept and professors still teach.

Figure 4. Subset of the LRT after recent housekeeping.

Same lessons here as usual…
Add generic taxa to your cladogram. Stay away from suprageneric taxa. Stay away from genomics in deep time studies. You might have to do this outside the academic system because the current vertebrate paleontology textbooks and the professors who teach from this textbook still support these long-standing problems.

Bécel, A., et al. 2020.
Evidence for a prolonged continental breakup resulting from slow extension rates at the eastern North American volcanic rifted margin, J. Geophys. Res. Solid Earth, 125, e2020JB020093,
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.
Gheerbrant E, Amaghzaz M, Bouya B and Goussard F and Letenneur C 2014a. Discovery of the skull of Ocepeia (Middle Paleoceneof Morocco): First clude on the basal radiation of Afrotheria and Paenungulata (Placentalia). Journal of Vertebrate Paleontology Program and abstracts 2014:137.
Gheerbrant E, Amaghzaz M, Bouya B and Goussard F and Letenneur C 2014b. Ocepeia (Middle Paleocene of Morocco): The Oldest Skull of an Afrotherian Mammal. PLoS ONE. 9 (2): e89739. doi:10.1371/journal.pone.0089739.
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.


Sandy Koufax and the origin of Homo sapiens

For those who don’t know baseball,
Sandy Koufax (Fig. 1) was a Hall of Fame pitcher for the Los Angeles Dodgers in the 1960s. So, what does this southpaw hurler have to do with the origin of the primate, Homo sapiens?

Figure 1. Iconic photo of Dodger pitcher Sandy Koufax (ca. 1965) hurling a fastball.

Wilson et al. 2016
reported, the practice of killing at distance with the accuracy of a major league pitcher, acting in a group toward one target, may be the turning point that separated Homo sapiens from all other hominines. Hurling rocks with speed and accuracy was a new method for dispatching prey and dispersing both predators and enemies. If you’re on the receiving end, there is no defense against an avalanche of incoming rocks. More importantly, the risk of injury for the ‘pitcher’ is minimal because, hypothetically, prey and enemies can never get close. Of course, that hypothesis gets turned on its head when it comes to war against someone else who also knows how to hurl fastballs into the strike zone. Spearks and arrows would follow.

Figure 3. Scene from 2001: A Space Odyssey by director Stanley Kubrick. Not violence, but cooperation marked the genesis of humankind. Chimps are all about violence.
Figure 2. Scene from 2001: A Space Odyssey by director Stanley Kubrick, written by Arthur C. Clarke. Not violence, but cooperation marked the genesis of humankind. Chimps are all about violence. Humans trade. Humans are also capable of hurling baseball-sized stones with speed and accuracy.

While killing prey and driving off enemies at a distance is important,
as we discussed earlier, Stanley Kubrick and Arthur C Clarke got it wrong in their 1968 movie, 2001: a Space Odyssey (Fig. 2). It wasn’t the ability to kill our neighbors that drove us toward becoming human. It was the ability to be look past our initial fear, revulsion and instinct to destroy. Indeed, it was our ability to make friends with strangers, to trade, to share, to specialize in tasks according to individual talents that created the various innovations and cooperations that allowed our species to succeed, reproduce and dominate. Human innovation accelerates from contact with others. Conversely, innovation comes to a halt with isolation and suppression. While most people just grow up, have children and do their job, it must be said that occasional geniuses change science and culture with their ideas and discoveries. Then the rest of us learn from them and skills become widespread.

Figure 3. Neanderthal composite skeleton (left in red) to scale with extant human skeleton (right in white). Note the differences in chest size, bone length, pelvic shape, femoral insertion angle and skull size.

Wood et al. 2016
identified ‘prehistoric spheroids’ (= baseball-sized = 7.5cm rocks found in a South African cave (>1.6mya) as ‘thrown projectiles’. Turns out baseballs are nearly the ideal rock size for hurling. Larger rocks can’t be thrown as far. Smaller rocks are too little to hurt and kill.

Dr Andrew Wilson explained:
“Whilst other animals have been known to throw objects on occasion, none can match the speed, accuracy and distances that a trained human can achieve. Humans are uniquely specialised for throwing, both anatomically and psychologically. Throwing has played a vital role in our evolutionary past, enabling us both to hunt prey and to compete with other carnivores to scavenge carcasses. The ability to damage or kill prey at a distance not only expands the range of foods available, but also reduces the risk of close confrontation with dangerous prey.”

Wilson et al. 2016 revived a hypothesis that has been around for over a hundred years.

Wood 1870 wrote:
“To fling one stone with perfect precision is not so easy a matter as it seems, but the Australian will hurl one after the other with such rapidity that they seem to be poured from some machine; and as he throws them he leaps from side to side so as to make the missiles converge from different directions upon the unfortunate object of his aim.”

Figure 5. Insulted with nicknames like ‘caveman’ and ‘gorilla’ Hall of Fame Yankees catcher, Yogi Berra, was adept at throwing out base stealers, often a distance twice as far as the pitcher’s mound.
Figure 5. Turns out Yogi Berra and Sandy Koufax sometimes appeared in the same 1960s era photos.
Figure 5. Turns out, despite their differences, catcher Yogi Berra and pitcher Sandy Koufax sometimes appeared in the same photos.

What separates Homo sapiens from Homo neanderthalenis?
Other than skull differences, the skeleton (Fig. 3) is taller and more gracile in our species, more like Sandy Koufax (Figs. 1, 5). Did H. neanderthalis have an accurate fastball? Probably not given their robust build (Fig. 3) and eventual extinction.

Of course, this needs to be studied in detail. Yankee catcher of the same era, Yogi Berra (Fig. 4), was insulted with names like “Ape,” “Caveman,” and “Gorilla“, yet could fling a stinger twice as far as the pitcher’s mound (= all the way to second base) from a crouch and without a windup.

Isaac B 1987. Throwing and human evolution. The African Archaeological Review 5:3–17.
Wilson AD, Zhu Q, Barham L, Stanistreet I, Bingham GP 2016. A Dynamical Analysis of the Suitability of Prehistoric Spheroids from the Cave of Hearths as Thrown Projectiles. Scientific Reports, 2016; 6: 30614 DOI: 10.1038/srep30614
Wood JG 1870. Natural history of man; being an Account of the Manners and Customs of the Uncivilized Races of Men. George Routledge and Sons. New York, NY.


Herpetocetus enters the LRT with other ‘diminutive’ rorquals

Herpetocetus morrowi  
(van Beneden, 1872, El Adli, Deméré and Boessenecker 2014; UCMP 129450; late Miocene to early Pleistocene) was a small (“diminutive”) rorqual (e.g. gray whales, humpback whales) with a long straight rostrum and flat cranium. In Herpetocetus (Fig. 1) the premaxillae are expanded toward the cranium. The mandible was ventrally straight distinct from related taxa with a ventrally concave rostrum.

Figure 1. Skull of Herpetocetus morrowi, colors added here. Not the jugal (cyan), rather than the anterior squamosal among other identifications different than originally identified.

El Adli, Deméré and Boessenecker 2014 also looked at
the many poorly preserved specimens attributed to Herpetocetus.

Phylogenetic problems
The cladogram by El Adli, Deméré and Boessenecker 2014 correctly included Janjucetus at the base, but then omitted all desmostylians and inserted an unrelated archaeocete, Aetiocetus . Even so Caperea and the right whales nested apart from rorquals and cetiotheres. The basalmost mysticete taxon in the LRT (Fig. 2), Miocaperea, was not included in the El Adli, Deméré and Boessenecker 2014 cladogram.

Figure 2. The oreodont-mesonychid-hippo-desmoystlian-mysticete clade subset of the LRT including Herpetocetus.

Another cetothere,
Eomysticetus (Fig. 3) was also added to the LRT (Fig. 2) from rather scrappy remains. Cetotheres are considered transitional taxa because they have a naris on top of the rostrum, rather than the cranium, as in extant baleen whales.

A long pair of nasals marks cetotheres as primitive among whale workers.
In the LRT long nasals that position the naris midway to the tip of the rostrum in cetotheres is just a variable trait. Here’s a guess: Perhaps this ‘primitive’ trait is a neotonous trait related to the fact that adult cetotheres are the size of newborn extant rorquals. Just a guess following analysis that minimizes taxon exclusion.

Perhaps, the big problem is
all current whale workers still consider the traditional clade ‘Cetacea’ monophyletic and they are trying to figure out how toothed whales lost their teeth and developed baleen (e.g. Marx et al. 2016). The problem is, baleen whales never did this. They have a separate ancestry. By adding taxa, the LRT documents the convergence of toothed whales in one clade with baleen whales in a completely different clade (Fig. 2).

El Adli JJ, Deméré TA and Boessenecker  RW 2014. Herpetocetus morrowi (Cetacea: Mysticeti), a new species of diminutive baleen whale from the Upper Pliocene (Piacenzian) of California, USA, with observations on the evolution and relationships of the Cetotheriidae. Zoological Journal of the Linnean Society. 170 (2): 400–466.
Marx et al. 2016. Suction feeding preceded filtering in baleen whale evolution. Memoirs of Museum Victoria 75: 71–82.
Van Beneden PJ 1872. Les Baleines fossiles d’Anvers. Bulletins de L’Academie Royale des Sciences, des Lettres et des Beaux-arts 34:6-23.

wiki/Micromysticetus – not yet posted

Hesperocyoninae: not just dog ancestors

Let’s start with a definition from Wikipedia:
Hesperocyoninae are basal canids that gave rise to the other two canid subfamilies, the Borophaginae and Caninae.”

Figure 1. Subset of the LRT focusing on the Carnivora (basal Placentalia).

the large reptile tree (LRT, 1965+ taxa; subset Fig. 1) supports that definition with Hesperocyon gregarois (Fig. 1 in green) nesting basal to Borophagus (Fig. 3) and therefore more or less basal to Canis (Fig. 4). So far, no hesperocyonines are basal to Canis itself. Hesperocyoninae is a junior synonym for Canidae in the LRT, and Canidae includes hyaenas and cats now.

two hesperocyonines (Fig. 1 in green) nest with felines (cats; Fig. 5).

Figure 2. The extant linsang, Prionoon, is a hesperocyon-grade carinvore.

The LRT recovers a previous overlooked living hesperocyonine.
The extant linsang, Prionodon (Fig. 2), nests basal to hyaenas (Fig. 6), andit appears to be part of the basal radiation of canids = hesperocyonines.

Figure 3. Hesperocyon gregarius skull. USNM 437888.
Figure 3. Canis lupus, the wolf, nests as a sister to Crocuta in the LRT.
Figure 4. Canis lupus, the wolf. Note the long rostrum putting the orbit in the back half of the skull.

Here are some traditional gene-based clades and their traditional members
Not all are recovered by the LRT.

Canidae: Hesperocyoninae, Borophaginae and Caninae (= dogs, wolves, foxes)
Cynoidea: add Miacis (Fig. 7).
Caniformia: add Arctoidea (= bears, raccoons, pinnipeds (seals + sea lions)
Carnivora: add Feliformia ( = civets, otter civets, mongooses, hyaenas, cats)

Figure 5. Hesperocyon sp. skull compared to Paraenhydrocyon and Panthera.

Based on skeletal traits
the LRT does not support the hypothesis that cats and hyaenas are closer to civets and mongooses than to dogs and Miacis. Nor does it support the monophyly of the traditional clade, Pinnipedia.

Figure 6. Prionodon and Crocuta skulls. These two nest together in the LRT.

While becoming an expert on dogs,
present day NHM curator of vertebrate paleontology, Xiaoming Wang (1994) reported on the Hesperocyoninae. Unfortunately he included no extant taxa in his phylogenetic analysis. That makes the traditional clade Hesperocyoninae paraphyletic. This clade should have been expanded to include related extant taxa, like the wolf, cat and hyaena. Then the clade would have become monophyletic. And a junior synonym for Canidae.

Figure 1. Miacis, an Eocene ancestor to extant dogs, such as Canis.
Figure 7. Miacis, an Eocene ancestor to extant dogs, such as Canis.

Then there’s Prohesperocyon
Traditional workers (e.g. Wang 1994) considered Prohesperocyon (Fig. 8) a basal dog. According to Wikipedia, “Prohesperocyon is an extinct genus of the first canid endemic to North America appearing during the Late Eocene around 36.6 mya.”

Figure 1. Taxa in the origin and evolution of moles, Herpestes, Prohesperocyon and Talpa.
Figure 8. Taxa in the origin and evolution of moles, Herpestes, Prohesperocyon and Talpa.

When added to the LRT
a few years ago, Prohesperocyon nested between the mongoose, Herpestes (Fig. 8, and the common mole, Talpa (Fig. 8). So it’s a mole ancestor. Not a dog ancestor.

The LRT minimizes taxon exclusion like this.

Wang X 1994. Phylogenetic systematics of the Hesperocyoninae (Carnivora, Canidae). Bulletin of the American Museum of Natural History. 221: 1–207.
Wang, X, Tedford RH and Anton M 2010. Dogs: their fossil relatives and evolutionary history. Coumbia University Press.


Notatesseraeraptor enters the LRT alongside Dilophosaurus

Notatesseraeraptor frickensis
(Zahner and Brinkmann 2019; Late Triassic; (SMF) 06-1 and 09-2: cranium (SMF 09-2) and partial postcranial skeleton (SMF 06-1) of “a likely juvenile”; Figs. 1, 2) is a smaller sister to Dilophosaurus and then to Coelophysis in the the large reptile tree (LRT, 1962+ taxa) and the first theropod from Switzerland.

Figure 1. Notatesseraeraptor skull reconstructed.

By contrast
Zahner and Brinkman 2019 reported, “Notatesseraeraptor frickensis gen. et sp. nov. is an early diverging neotheropod with affinities to Dilophosaurus + Averostra and displays an interesting mixture of character states typically seen either in coelophysids or in dilophosaurids. Based on our phylogenetic analysis N. frickensis gen. et sp. nov. is considered one of the currently oldest and most basal members of the lineage, leading to Averostra. A monophyletic ‘traditional Coelophysoidea’ including Dilophosaurus is not supported.”

Figure 2. Notatesseraeraptor at full scale on most computer monitors. Skull length 22.5cm.

(Fig. 3) indicates this lineage did not lead to Averostra. So the phylogeny is controversial.

Averostra According to Wikipedia, “the group was re-defined by Martin Ezcurra and Gilles Cuny in 2007 as a node-based clade containing Ceratosaurus nasicornis, Allosaurus fragilis, their last common ancestor and all its descendants.”

In the LRT (subset Fig. 3) this is a much smaller clade not related to Coelophysis and kin.

Figure 3. Subset of the LRT focusing on basal theropods. Averostra is a small clade here.

Zahner and Brinkman report,
“Hypotheses on early neotheropod relationships still agree little. The assignment of several taxa to the Coelophysoidea is uncertain and the monophyly of the clade Dilophosauridae is controversial.”

The LRT agrees with the authors that Notateserraeraptor is close to Dilophosaurus. Let’s see what the issues are.

Neotheropoda According to Wikipedia at least three authors since 2015 have included different taxa in their cladograms of this clade. Bakker 1986 defined the clade to exclude coelophysids. “However, most later researchers have used it to denote a broader group. Neotheropoda was first defined as a clade by Paul Sereno in 1998 as Coelophysis plus modern birds, which includes almost all theropods except the most primitive species. Dilophosauridae was formerly considered a small clade within Neotheropoda, but was later considered to be paraphyletic.”

Experts need to stop redefining taxa.

Coelophysoidea According to Wikipedia at least three authors since 2005 have included different taxa in their cladograms of this clade, some known from scraps.

Dilophosauridae Wikipedia redirects the reader to Neotheropoda, which includes Coelophysoidea

Was Notatesseraeraptor a juvenile?
Given that archosaur juveniles have ‘cute’ features (a short rostrum and large orbit) and Notatesseraeraptor lacks these traits (Figs. 1, 2), it was a small adult. Living in the Triassic it was ancestral to Dilophosaurus in the Early Jurassic.

Zahner M and Brinkman W 2019. A Triassic averostran-line theropod from Switzerland and the early evolution of dinosaurs. Nature Ecology & Evolution 3:1146–1152.

wiki/ Notatesseraeraptor

Platylitholophycus: Plant – no. Squid – no. Elasmobranch – yes.

How did this happen?
From the Bronson and Maisey 2018 abstract:
Misidentified fossils are common in paleontology, but Platylithophycus has undergone a particularly problematic series of descriptions. The holotype of P . cretaceus comes from the Upper Cretaceous Niobrara Chalk of Kansas, and was first described as a calcareous green alga, based on the surface texture of the specimen. Later, Platylithophycus was re-identified as a sepiid cephalopod, based partly on a comparison of microstructure between P . cretaceus and the pen of modern squids. Platylithophycus then became part of the University of Nebraska teaching collection, where, according to paleontological legend, an undergraduate student suggested that the fossil’s tessellated surface looked a lot like shark cartilage. However, that interpretation has not been formally proposed until now. This work re-describes the holotype of Platylithophycus cretaceus as part of the branchial endoskeleton of an elasmobranch, based on both gross morphology and ultrastructure, including recognizable tessellated cartilage with intertesseral pores and joints.”

According to the,
There are many examples of temporarily misplaced taxa in paleontological history, including ferns that were once thought to be sponges and lungfish teeth thought to be fungi,” said the lead author, Allison Bronson, a comparative biology Ph.D.-degree student in the Museum’s Richard Gilder Graduate School. “In this case, the misidentification didn’t happen because of a lack of technology at the time—scientists familiar with cartilage structure could easily see this was a chondrichthyan fish. The researchers used reasonable arguments for their interpretations, but didn’t look outside of their own fields.”

Figure 1. Platylithophycus cretaceum

According to the,
“In 1948, two paleobotanists from the Colorado School of Mines and Princeton University compared the texture of the fossil slab with that of green algae. They described two parts of a plant: surfaces covered with hexagonal plates, which they called “fronds,” and supposedly calcium carbonate-covered thread-like filaments. In 1968, two researchers from Fort Hays Kansas State College studying cephalopods from the Niobrara Formation compared the specimen with a cuttlefish, based primarily on its textural similarities to a cuttlebone—the unique internal shell of cuttlefish. The reclassification made Platylithophycus the oldest sepiid squid then on record.”

Figure 2. Platylithophycus duplicated and flipped along the parasagittal plane and compared to the manta ray, Manta. Based on the exposed fossil the view is from the stomach anteriorly toward ever larger gill arches getting closer to the larger mouth rim.

According to the,
“‘We think this was a rather large cartilaginous fish, possibly related to living filter-feeding rays such as Manta and Mobula,” [Fig. 2] Maisey said. “This potentially expands the range of diversity in the Niobrara fauna.’ But because this fossil only preserves the animal’s gills and no additional identifying features like teeth, it cannot be given a new name or reunited with an existing species. So until then, this fish will still carry the name of a plant.”

Bronson AW and Maisey JG 2018. Resolving the identity of Platylithophycus, an enigmatic fossil from the Niobrara Chalk (Upper Cretaceous, Coniacian–Campanian). Journal of Paleontology 92(4):1-8


Haikouella: an early Cambrian chordate with craniate traits

Chen, Huang and Li 1999 bring us news of
305 specimens of Haikouella (Figs. 1), a semi-craniate (sense organs, but no skull) from the Early Cambrian if China. It nests between lancelets and hagfish in the LRT (Fig. 2).

From the abstract
“Since the identification of the Lower Cambrian Yunnanozoon as a chordate in 1995 (ref. 1), large numbers of complete specimens of soft-bodied chordates from the Lower Cambrian Maotianshan Shale in central Yunnan (southern China) have been recovered. Here we describe a recently discovered craniate-like chordate, Haikouella lanceolata, from 305 fossil specimens in Haikou near Kunming. This 530 million-year-old (Myr) fish-like animal resembles the contemporaneous Yunnanozoon from the Chengjiang fauna (about 35 km southeast of Haikou) in several anatomic features. But Haikouella also has several additional anatomic features: a heart, ventral and dorsal aorta, an anterior branchial arterial, gill filaments, a caudal projection, a neural cord with a relatively large brain, a head with possible lateral eyes, and a ventrally situated buccal cavity with short tentacles. These findings indicate that Haikouella probably represents a very early craniate-like chordate that lived near the beginning of the Cambrian period during the main burst of the Cambrian explosion. These findings will add to the debate on the evolutionary transition from invertebrate to vertebrate.”

Figure 1. Haikouella in situ and diagrams. Colors added here. Blue is the atrium.
Figure 2. Haikouella is added to the LRT and nests here, among basal chordates.

The WordPress layout program is still causing trouble. The layouts and previews do not match the published work. Hopefully this one will not be different in graphic appearance from the 3600 or so that preceded it.

Chen J-Y, Huang D-Y and Li C-W 1999. An early Cambrian craniate-like chordate. Nature 402:518–522.