Revisiting Cambaytherium: replacing those displaced bone splinters

According to Wikipedia – Cambaytherium
“Cambaytherium was a genus of herbivorous four-legged quadrupeds.”

That’s about as general as can be imagined.

“Cambaytherium is considered to be close to the ancestry of Perissodactyla, the odd-toed ungulates. An analysis published in 2019 placed the Cambaytheriidae as most closely related to the anthracobunids in the order Anthracobunia, a sister group to the true perissodactyls.”

Confirming those considerations,
in the large reptile tree (LRT, 2319 taxa) Cambaytherium (Fig 1) nests with Anthracobune (Fig 2).

By contrast
those two nest between hippos and desmostylians in the LRT, which puts all these taxa up to their necks in water and apart from the origin of Perissodactyla (= horses and rhinos).

Figure 1. Cambaytherium parts. Colors added here. Here arrows point to bone splinters that are moved back to their invivo positions.

Between the two of them,
Anthracobune and Cambaytherium both provide Bauplans for the missing parts in the other. Using Anthracobune helped restore missing parts and find bone splinters that fill gaps in Cambaytherium (Fig 1).

Figure 3. Anthracobune reconstructed with a larger skull to match the teeth on the mandible.

This is why
you would be wise to revisit your data when things ‘start to gel’ = “to become clearer and more definite, to work well.”

Cambaytherium thewissi 
(Rose et al. 2014; Eocene, 55 mya; 45-75 lbs) was originally considered a basal perissodactyl, but nests here with Anthracobune. They both had a posterior mandible with a long retroarticular process.  Cambaytherium was found on the marine coastline of island India, close to where pakicetid aand archaeocete whales were convergently evolving from terrestrial tenrec ancestors.

Anthracobune pinfoldi
(Pilgrim 1940; Kumar 1991, middle Eocene, size of a small tapir) The anthracobunids were originally considered proboscideans, like Elephas. Cooper et al. 2014 nested them with perissodactyls, like Ancodus. Here they nest with the mesonychids between Hippopotamus and the desmostylian Paleoparadoxia. Anthracobunids have small and simple upper and lower incisors and relatively small canines. The naris opens dorsally signaling a greater aquatic niche. The retroarticular process is the largest among all mammals. The mandible is longer than the rostrum.

Figure 4. Repairing the apparent mandibular fenestra in the didelphid Ambolestes by shifting a bone splinter.

On a similar notem but on another family tree branch:
and distinct from all other mammals, the didelphid marsupial Ambolestes was preserved with what appears to be a mandibular fenestra (Fig 4). Since no other relatives have such a fenestra, this appears to be due to a displaced splinter of bone replaced to its invivo position here (Fig 4).

References
Cooper LN, Seiffert ER, Clementz M, Madar SI, Bajpai S, Hussain ST, Thewissen JGM 2014. Anthracobunids from the Middle Eocene of India and Pakistan Are Stem Perissodactyls. PLoS ONE. 9 (10): e109232. doi:10.1371/journal.pone.0109232. PMID 25295875.
Cope ED 1873. Fourth notice of extinct Vertebrata from the Bridger and the Green River Tertiaries. Paleontological Bulletin 17:1–4.
Kumar K 1991. Anthracobune aijiensis nov. sp. (Mammalia: Proboscidea) from the Subathu Formation, Eocene from NW Himalaya, India”. Geobios. 24 (2): 221–39. doi:10.1016/s0016-6995(91)80010-w. OCLC 4656806310.
Pilgrim GE 1940. Middle Eocene mammals from north-west Pakistan. Proceedings of the Zoological Society. B. London. 110: 127–152.
Rose, KD et al. (8 other authors) 2014. Early Eocene fossils suggest that the mammalian order Perissodactyla originated in India. Nature Communications. 5 (5570). doi:10.1038/ncomms6570.
Rose KD et al, 2020. Anatomy, Relationships, and Paleobiology of Cambaytherium (Mammalia, Perissodactylamorpha, Anthracobunia) from the lower Eocene of western India, Journal of Vertebrate Paleontology (2020). DOI: 10.1080/02724634.2020.1761370

wiki/Cambaytherium
wiki/Achaenodon
wiki/Anthracobune

Avicranium 2024: mistakes galore

Buffa et al 2024 hoped to convince readers
that their freehand drawings of the skull of Avicranium (Figs 1, 2) were superior data to the µCT scans of Pritchard and Nesbitt 2017. Buffa et al reported, “Contrary to previous interpretations, the entire rostrum and most of the palate are not preserved in this specimen.”

Freehand reconstructions are always biased due to artistic inaccuracy. Don’t freehand, if possible. Instead, borrow the scans from the earlier studies (Fig 2).

In 2018 Avicranium was reconstructed anew (Fig 2) with a premaxilla and maxilla based on the Bauplan of sister Vallesaurus. Buffa et al are mistaken in their assertion, identification and reconstruction of rostral elements.

To make matters worse
Buffa et al reported they reconstructed Avicranium based on the Bauplan of Megalancosaurus – even though they nested Avicranium with Vallesaurus, confirming the nesting in the LRT in 2018 (Fig 2).

Figure 1. The freehand skull of Aviranium reconstructed by Buffa et al (left) and the µCT scanes Pritchard and Nesbitt (right). Buffa report they based their reconstruction on Megalancosaurus, but nested Avicranium with Vallesaurus. That not good science. See figure 2 frame 3 for a reconstruction based on µCT scans and Vallesaurus.

To make matters even worse,
Buffa et al had no idea that reptiles divided into Lepidosauromorpha and Archosauromorpha in the Viséan (Early Carboniferous). They reported, “The Late Permian Epoch witnessed the origin of both archosauromorphs and lepidosauromorphs, which together make up the clade Sauria, or crown-group reptiles.” ‘Sauria’ means Buffa et al wrongly assumed Synapsida split off earlier. Synapsida are members of the Archosauromorpha in the LRT.

On a similar note:
Buffa et al had no idea that the diapsid-type skull evolved twice by convergence. Colleagues, put the past behind you. It’s time to get up-to-date. Add taxa to find this out for yourself. The LRT has been online for 13 years as of today.

Taxon exclusion pervaded their cherry-picked cladogram.
Buffa et al reported, “However, much remains unknown of the early history of trilophosaurids and drepanosauromorphs, and of the evolution of arboreality in Triassic archosauromorph reptiles.”

There is a reason for their lack of understanding.  In the LRT trilophosaurids and drepanosauromorphs are both lepidosaurs, not archosauromorphs. AND they are not related to one another in the LRT.

Contra Buffa et al much IS known of the early history of trilophosaurids and drepanosauromorphs all the way back to EarlyCambrian fish and earlier worms. Buffa et al omitted the basalmost drepanosauromorph in the LRT, Jesairosaurus. Add taxa to find this out for yourself.

Figure 2. Avicranium from Pritchard and Nesbitt 2017, in situ, original reconstruction and revised with rostral restoration based on its sister, Vallesaurus.

An earlier look at Avicranium
in 2018 offered a new reconstruction (Fig 2 frame 3) in which the most gracile portions of the skull were restored based on an LRT sister, Vallesaurus (Fig 5).

Figure 3. Cherry-picked cladogram from Buffa et al 2024, modified to fit. Here aquatic Claudiosaurus is basal to the ‘rib’ gliders. Red flag. Rhynchosauru are basal to proterosuchids. Red flag. Tanystropheids are basal to azhendohsaurs. Red flag. Here, following academic traditions, Buffa et al shuffled  lepidosauromorphs between archosauromophs. Note the absence of pterosaurs from this study that includes Ornithodira. Note the absence of pterosaurs despite the appearance here of Ornithodira. This list of problems here goes on and on.

Was surprised to see the absence
of Drepanosaurus (Fig 5) n the LRT. So it was added (finally!), nesting between Hypuronector and the more derived taxa, like Megalancosaurus. No surprise there.

Following academically approved traditions
Buffa et al shuffled lepidosauromorphs between archosauromophs. Unfortunately they did not check their results. In Buffa et al aquatic Claudiosaurus is basal to the ‘rib’ gliders. Red flag. Herbivorous yhynchosaurs are basal to piscivorous proterosuchids. Red flag. Long-necked tanystropheids are basal to bulky azhendohsaurs. Red flag. They also recover Parareptilia and other invalid clades.

Figure 4. Drepanosaurids to scale. Gray areas are not to scale. The skull of Avicranium should be based on the Bauplan of Vallesaurus.

Add taxa
to your own homebuilt LRT. Don’t borrow untested cladograms based on trust, no matter how academically approved they are. Don’t make unforced phylogenetic errors based on taxon exclusion. If you have to use the LRT like an index to check for taxon exclusion.

Figure 5. Subset of the LRT focusing on drepanosaurids and their relatives. Buffa et al recovered Trilophosaurus alongside the drepanosaurs. Here the two are not related except distantly. Buffa et al omitted Jesairosaurus.

Check your results
to make sure sister taxa look like they could have evolved from one another. Swimmers don’t often evolve into ‘rib’ gliders. Rhynchosaurs, with their bizarre dentition, are terminal taxa, not transitional to proterosuchids. That role belongs to similar protorosaurs.

Try to choose the correct Bauplan
based on phylogenetic analysis. Don’t cherry-pick another Bauplan like Buffa et al did. Choose the sister taxon, especially if you know the sister taxon.

The problem with the invalid clade, ‘Avicephala’
(in the Buffa et al headline) was reviewed here in 2021.

References
Buffa V, Frey E, Steyer J-S and Laurin M 2024. ‘Birds’ of two feathers: Avicranium renestoi and the paraphyly of bird-headed reptiles (Diapsida: ‘Avicephala’). Zoological Journal of the Linnean Society 2024, XX:1–25.
Pritchard AC and Nesbitt SJ 2017. A bird-like skull in a Triassic diapsid reptile increases heterogeneity of the morphological and phylogenetic radiation of Diapsida. Royal Society Open Science DOI: 10.1098/rsos.170499.

wiki/Vallesaurus
wiki/Avicranium

Avicranium: a 3D drepanosaur skull

 

Revisiting Dissacus: now a sister to Meniscotherium

According to Wikipedia,
“Dissacus 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.”

Yes. It looks like a mesonychid… but it looks a little more like something else.

Figure 1. Dissacus in several views. Colors added here.

According to the LRT
Dissacus (Fig 1) nests within the clade Condylarthra, convergent with mesonychids. Dissacus descendants evolved into sheep-like herbivores, like Meniscotherium (Fig 2), followed by larger elephant-like herbivores, like Astrapotherium (Fig 3). This clade has no extant representatives.

Figure 2. Meniscotherium skull. In this is a smaller predecessor to Astrapotherium note the genesis of maxillary tusks here and then longer dentary when the teeth are matched to occlude correctly. Note the overlapping lacrimal.

Dissacus zanabazari
(Cope 1881; Geisler and McKenna 2007; Early Eocene) was traditionally considered a mesonychid, but here nests basal to Meniscotherium, without molarized premolars and a reduced lacrimal overlap of the jugal. Note the separation of the lateral premaxillae as in Meniscotherium. Yes, this could be taphonomy. More specimens will tell us.

Figure 3. Meniscotherium enlarged and to scale with Astrapotherium.

Meniscotherium tapiacitum
(Cope 1874; Williamson and Lucas 1992; Middle Eocene 54-38 mya; 25-50 cm long) nests with Astrapotherium (below) in a clade near the base of the Condylarthra. Considering the Paleocene date for Astrapotherium, Meniscotherium probably originated earlier, perhaps in the Cretaceous. The incisor canines were reduced here. That happens because fossils are so rare. Look for trends in evolution. Exceptions will occur.

If you’re wondering about the outgroup sister clade
to Dissacus and kin, here they are (Fig 4), a rather obscure clade of herbivores.

Figure 4. Dissacus compared to Conoryctes and Psittacotherium.

The outgroup for the Dissacus clade
included Conoryctes and Psittacotherium (Fig 4), both from the Paleocene. None of the above taxa are carnivores.

This hypothesis of interrelationships
now requires a test with a similar taxon list and your own characters for confirmation, refutation or modification.

References
Cooper LN, Seiffert ER, Clementz M, Madar SI, Bajpai S, Hussain ST, Thewissen JGM 2014-10-08. Anthracobunids from the Middle Eocene of India and Pakistan Are Stem Perissodactyls. PLoS ONE. 9 (10): e109232. doi:10.1371/journal.pone.0109232. PMID 25295875.
Cope ED 1872. Descriptions of some new Vertebrata from the Bridger Group of the Eocene. Proceedings of the American Philosophical Society 12:460-465.
Cope ED 1874. Report of the Chief of Engineers for. 1874 Vol. II, Pt. II, Appendix FFa of Appendix FF, pp. 115-130.
Cope ED 1881. Notes on Creodonta. American Naturalist 15: 1018–1020.
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.

wiki/Meniscotherium
wiki/Dissacus

Revisiting Early Paleocene Triisodon and two tiny mesonychids

Housekeeping continues
in the mammal subset of the LRT.

As of today
an Early Paleocene mesonychid, Triisodon, nests with two phylogeneticaly mniaturized mesonychids, early Oligocene Didymoconus from Asia and Paleoene Ocepeia (Fig 1) from Morocco. These latter two tiny taxa (Fig 1) apparently led to no other taxa. This clade of three taxa is basal to the one that produced the large extant mammal, Hippopotamus. All are derived from Mesonyx (Fig 2), a plant-eater with molars flattened by a lifetime of grinding and crushing tough vegetation, such as grasses and reeds, as in hippos.

Figure 1. Triisodon and the tiny hippos, Wyolestes (= Didymoconus) and Ocepeia.

According to Wikipedia – Mesonyx,
“They were probably active hunters.” This is widely believed, but incorrect based on phylogeny and tooth wear. Hippos and their relatives are and were herbivores, but the defensive tusks of fossil taxa have been mistaken for offensive fangs in mesonychid-hippos like Early Miocene Simbakubwa of Kenya (hippo territory).

Figure 2. Harpagolestes and kin inluding Mesonyx and Triisodon.

Triisodon quivirensis
(Cope 1881; Early Paleocene) is a basal mesonychid known from most of a 3D skull. Note the large canine. The premaxillary teeth have three cusps. Cope 1881 considered this ‘the oldest known mammal’, suggesting an earlier, perhaps Cretaceous, origin for mesonychids and their ancestors.

Didymoconus berkeyi
(Gingerich 1981, IVPP V11983, Eocene 52mya) is a former enigma taxon here nesting with the small mesonychid, Ocepeia. The zygomatic arches are wider posteriorly and the orbits are dorsally open, distinct from Ocepeia, which also has dorsally open orbits.

Ocepeia daouiensis
(Gheerbrant et al 2001, 2014; Paleocene, 60 mya; 9 cm skull length) is a phylogentically miniaturized mesonychid from Morocco and a sister to Didymoconus. The pneumatized skull contains many air spaces. Slightly larger skulls have larger canines and so are considered male. This specimen (Fig 1) has a tiny canine. The molar teeth are very large and the jugal deepens below the orbit, hiding the posterior molars in lateral view. The premaxilla is transverse. The upper canine rubs against the lower one creating a facet, as in hippos and mesonychids. Ocepeia was found with aquatic taxa and was probably amphibious. The name Ocepeia derives from the initials of Office Chérifien des Phosphates (O.C.P.), the national Moroccan phosphate mining company.

According to Wikipedia – Mesonyx,
“In the generally accepted cladogram by Spaulding et al. (2009), Mesonyx is classified, together with other mesonychians, outside of ungulates.”

Some of this is confirmed in the LRT, which tests more taxa.
A closer interrelationship between mesonychids, hippos and mysticetes (= not all ‘cetaceans’) is recovered. Also arising from Mesonyx: artiodactyls, beginning with the Miocene Homalodotherium + Cainotherium clades. Perissodactyls in turn arise from the artiodactyls, specifically from the Early Eocene Litolophus + Lophiodon clades. So parts of the Spaulding et al 2009 cladogram are upside down when more taxa are included.

Add taxa to confirm, refute or modify this hypothesis of interrelationships.

By the late Miocene
the Mesonyx – hippo – desmostylian line had produced Miocaperea, a basal mysticete (baleen whale), about the time the first pig relatives are recovered, but much later than the earliest horse relatives. So the Paleocene remains an under-explored radiation event.

According to Wikipedia – Didymoconidae,
citing Morio and Nagel 2002, “Its classification has been the subject of controversy, and the family has been placed in various orders since it was erected in 1943, sometimes being placed in its own order Didymoconida.

According to Morlo and Nagel, Three prior authors ‘regarded’ didymoconids as mesonychids, matching the LRT. Other prior authors ‘regarded’ didymoconids as members of the Lipotyphla, Creodonta, Caniformia, Arctocyonoidea, Palaeoryctoidea and Leptictida. Most of these are not related to one another in the LRT.

According to Wikipedia – Ocepeia,
the presented cladogram nested Ocepeia with the giant otter shrew, Potamogale, close to Orycteropus, the aardvark, and Ptolemaia, a basal condylarth. None of these are related to one another in the LRT.

References
Cope ED 1872. Descriptions of some new Vertebrata from the Bridger Group of the Eocene. Proceedings of the American Philosophical Society 12:460-465.
Cope ED 1881. On Some Mammalia of the Lowest Eocene Beds of New Mexico. Proceedings of the American Philosophical Society. 19 (109): 484–495.
Gheerbrant E, Amaghzaz M, Bouya B and Goussard F and Letenneur C 2014. Ocepeia (Middle Paleocene of Morocco): The Oldest Skull of an Afrotherian Mammal. PLoS ONE. 9 (2): e89739. doi:10.1371/journal.pone.0089739.
Gingerich PD 1981. Radiation of Early Cenozoic Didymoconidae (Condylarthra, Mesonychia) in Asia, with a New Genus from the Early Eocene of Western North America. Journal of Mammalogy 62(3):526-538.
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.
Morlo M and Nagel D 2002. New Didymoconidae (Mammalia) from the Oligocene of Central Mongolia and first information on the tooth eruption sequence of the family. Neues Jahrbuch für Geologie und Paläontologie – Abhandlungen. 223 (1): 123–144.
Szalay FS and Gould SJ 1966. Asiatic mesonychidae (Mammalia, Condylarthra). Bulletin of the American Museum of Natural History 132(2):127–174
Wortman JL 1901. Studies of Eocene Mammalia in the Marsh Collection, Peabody Museum. The American Journal of Science, series 4 12(70):281-296.

wiki/Mesonyx
wiki/Harpagolestes
wiki/Ocepeia
wiki/Triisodon
wiki/Didymoconus
wiki/Simbakubwa

 

Early Eocene Alocodontullum: now an aardvark and anteater ancestor

Rose, Emry and Gingerich 1992 reported,
“A substantially complete skeleton of the early Eocene palaeanodont Alocodontulum atopum from the Bighorn Basin, Wyoming, is described. It is the oldest and most complete known skeleton referable to the family Epoicotheriidae.”

The skull of Epoicotherium, a type of fairy armadillo, is shown below (Fig 4).

Figure 1. The aardvark, Orycteropus, compared to the much smaller and earlier, Alocodontullum, in which the skull was not described, perhaps missing. Note the digging forelimbs.

Here
in the large reptile tree (LRT, 2319 taxa, subset Fig 3) Alocodontulum nests basal to Orycteropus, the extant aardvark (Fig 1), pangolins, anteaters and armadillos.  Rose, Emry and Gingerich mentioned and compared Alocodonulum to Manis, the pangolin, several times, but did not mention ‘aardvark’ or ‘Orycteropus‘.  The Epoicotherium clade of fairy armadillos and kin is a sister to this clade in the LRT.

Dasypus evolved armor by convergence with glyptodonts retained by fairy armadillos.

Figure 2. Alocodontullum the first round reconstruction from several years ago) compared to scale with Metacheiromys, a middle Eocene almost toothless taxon.

Rose, Emry and Gingerich 1992 concluded,
“UM 93740, allocated to Alocodontulurn atopum, is the oldest and most nearly complete
epoicotheriid skeleton known. The skeleton represents an animal about the size of a small
armadillo (Euphractus or Daypus), with a head-body length of roughly 30 cm and a body
weight estimated at approximately 1-2 kg.”

“Alocodontulum is the most fossorially adapted mammal known from the early Eocene of
North America. It was probably armadillo-like in being generally terrestrial (not obviously
subterranean) but a very proficient burrower.”

Earlier these two taxa (Fig 2) nested closer to the basal condylarth Vulpavus.

Figure 3. Subset of the LRT focusing on Xenarthra, the edentates.

According to Wikipedia,
“Metacheiromys was a small creature, and measured around 45 centimetres (18 in) long. It had long claws and a narrow head similar in shape to that of an armadillo or an anteater (though it was actually related to the modern pangolins).”

Figure 4. Epoicotherium skull in several views. Colors added here.

Rose 2008 reported,
“Despite relatively complete osteological knowledge of several species, the relationships of palaeanodonts remain controversial. They are usually considered to be related to either Xenarthra or Pholidota (or both), but conclusive evidence of their affinities is lacking.”

In the LRT these taxa are ALL related to one another.

Gaudin et al 2009 sought to map out
the phylogeny of the pangolins. Unfortunately they cherry-picked two unrelated outgroup taxa, the palm civet, Nandinia, and the hedgehog, Erinaceus. Correctly they also nested Metacheiromys as a third outgroup taxon.

Note sure why hedgehogs as so popular as outgroup taxa. Clearly hedgehogs are not plesiomorphic relative to bats and/or pangolins.

Alocodontullum atopum
(Rose, Bown and Simons 1978; Rose, Emery and Gingerich 1992; early Eocene, 45 cm in length; UM 93740) is a close relative of Metacheiromys differing chiefly in relative metatarsal and toe lengths and having flat-cusped teeth posterior to the short upper canines with long root. Claws and forelimbs appear ready to dig.

Today’s post is a result of recent housekeeping in the mammal subset of the LRT, correcting freshman errors along the way. In the LRT (subset Fig 3) Xenarthra includes more taxa than university textbooks and academic experts currently indicate.

References
Gaudin TJ, Emry RJ and Wible JR 2009. The phylogeny of living and extinct pangolins (Mammalia, Pholidota) and associated taxa: A morphology based analysis. Journal of Mammal Evolution 16:235–305.
Rose KD, Bown TM and Simons EL 1978. Alocodontulum, a new name for Alocodon Rose, Bown and Simons 1977, non Thulborn, 1973. Journal of Paleontology 52(5):1162.
Rose KD, Emery RJ and Gingerich PD 1992. Skeleton of Alocodontulum atopum, an early Eocene Epoicotheriid (Mammalia, Palaenodonta) from the Bighorn Basin, Wyoming.
Rose KD 2008. Palaeanodonta and Pholidota, chapter 9:135–146.

wiki/Alocodontullum – not yet posted
wiki/Epoicotheriidae

 

Mammalodon and Janjucetus move to the odontocete clade

Traditional ‘toothed’ mysticetes,
Mammalodon and Janjucetus (Fig 1), were always a little different than the other mysticete ancestors in the large reptile tree (LRT, 2319 taxa). As of today those differences are no longer a factor. Scoring changes move both close to Aetiocetus (Fig 1), a transitional archaeocete – odontocete without a melon, but with single-rooted premolars and molars.

Corrections like this are part of the scientific method.

Figure 1. Aetiocetus, Janjucetus and Mammalodon to scale.

The long low snout pf Aetiocetus is reduced
in Mammalodon and Janjucetus (Fig 1). Earlier the LRT nested these two with a similar short-snouted taxon, Anthracobune (Fig 2), a taxon that continues to link hippos with desmostylians + mysticetes in the LRT.

The problem that raised a curious eyebrow
was the retroarticular process. It was extremely long in Anthracobune (Fig 2) – and missing in Janjucetus and Mammalodon (Fig 1).

I should have tested this earlier.
We looked at convergent mysticete-odontocete taxa a few days ago.

Figure 3. Anthracobune reconstructed with a larger skull to match the teeth on the mandible.

My guess is
a much smaller phylogenetically miniaturized transitional taxon will someday be discovered that more closely links long-snouted Aetiocetus (Fig 1) with its short-snouted (neotonous), but not smaller relatives, Mammalodon and Janjucetus. Presently these two taxa are terminal. They stand alone morphologically. Presently long-snouted taxa gave rise to long-snouted odontocetes like Simocetus and Physeter (the extant sperm whale). By ccontrast, dolphins have a shorter snout – by convergence with Janjucetus and Mammalodon – also by phylogenetic miniaturization and neotony according to the LRT.

Whale workers will tell you
that Aetiocetus, Janjucetus and Mammalodon are mysticete ancestors (Fordyce and Marx 2016, Geisler et al 2017). This works – but only in the absence of pertinent taxa found in the LRT that completely separate odontocete ancestors from mysticete ancestors.

Add taxa to your own LRT to find out for yourself. Apologies for earlier errors.

Janjucetus hunderi
(Fitzgerald 2006; late Oligocene; est. 3.5m in length) was originally considered the basalmost Mysticeti (baleen whale), but it had large serration teeth, the whale-like post-crania imnagined by Fitzgerald is supported by phylogenetic bracketing, but this is a relative of Aetiocetus, basal to Odontoceti (toothed whale). The skull was more than twice as wide as tall. The orbit was at mid skull, not in the posterior half, as in related taxa. This is a result of phylogenetic miniaturization and neotony.

Mammalodon colliveri
(Pritchard 1939; Late Oligocene, est 3 m in length) was previously considered a basal mysticete with teeth, closely resembling Janjucetus. Here it nests with Janjucetus and archaeocetes leading to odontocetes. The snout is shorter than the cranium.

Mammalodon hakataramea
Fordyce and Marx 2016)

References
Emlong D 1966. A new archaic cetacean from the Oligocene of Northwest Oregon. Bulletin of the Museum of Natural History, University of Oregon. 3: 1–51.
Fitzgerald EMG 2006. A bizarre new toothed mysticete (Cetacea) from Australia and the early evolution of baleen whales. Proceedings of the Royal Society B 273:2955-2963.
Fordyce RE and Marx FG 2016. Mysticetes baring their teeth: a new fossil whale, Mammalodon hakataramea, from the Southwest Pacific. Memoirs of Museum Victoria 74: 107–116.
Geisler JH; Boessenecker RW; Brown M; Beatty BL 2017. The Origin of Filter Feeding in Whales. Current Biology. 27 (13): 2036–2042.e2. doi:10.1016/j.cub.2017.06.003
Pritchard G B 1939. On the discovery of a fossil whale in the older tertiaries of Torquay, Victoria. The Victorian Naturalist 55:151-159.

wiki/Aetiocetus
wiki/Janjucetus
wiki/Mammalodon

A basal baleen whale with vestigial desmostylian molars

While academic whale workers continue to seek without success
toothless mysticete ancestors in the Archaeoceti (e.g. Bisconti M 2012 and links below) the LRT recovered a Miocene (11-7mya) mysticete, Miocaperea pulchra, with fossil baleen AND vestigial, but desmostylian-like, molars (Figs 1, 2). Bisconti 2012 overlooked the teeth and called Miocaperea,  “A fossil pygmy right whale with exquisitely preserved baleen.”

Baleen is made of keratin, like hair and fingernails, so preservation is rare.

Figure 1. Miocaperea is a Miocene mysticete with vestigial molars. Its a giant desmostylian. Compare to Desmostylus to scale at lower right.

Miocaperea pulchra
(Bisconti 2012; late Miocene, 7–8 Ma; 40cm skull length) was considered a Miocene ancestor of Caperea (Figs 3, 4). The post-crania in Miocapera is not known, so it could have had legs or flippers, or some sort of transitional structure.

Figure 2. Miocaperea baleen from the Miocene.

Bisconti did not mention teeth
or desmostylians in his text. Instead he listed the toothed whales, Aetiocetius, Zygorhiza, Dorudon, Georgiacetus and Protocetus as outgroup taxa along with Mammalodon, a taxon nesting between hippos and desmostylians in the LRT.

So taxon exclusion was an issue and a handicap for Bisconti back in 2012. The traditional clade Cetacea was invalidated here in 2016, so Bisconti was following tradition.

Here is a report on the fossil chin of an Australian mysticete
“at least 10 million years older”, (19mya, Early Miocene, Rule et al 2023) shown on the video below.

You might find an online NatGeo article titled,
“Prehistoric toothless whale among oldest” at 36 million years ago. This was about Mystacodon, a toothed odontocete ancestor, perhaps with legs. This claim was debunked earlier, links below.

You also might find an online SDSU article titled,
“Ancient baleen whales had a mouthful. Ancient CD scanes of a 25 million year-old fossil skull show the Aetiocetus weltoni had both teeth and baleen, unlike modern whales.” What they found is ‘neurovascular evidence’ in a toothed whale for which they report, “Fossils reveal that the earliest mysticetes possessed an adult dentition.”

This, again, is incorrect and an ongoing myth based on taxon exclusion.

Peredo, Pyenson and Uhen 2022 also debunked this hypothesis,
and they reported, “the oldest direct evidence of fossil baleen is ~ 27 million years younger than the oldest stem mysticetes” citing Esperante et al 2008. Note: they said ‘oldest’ and ‘younger’, which is a confusing way to state an earliest age for baleen.

Strangely, the authors did not cite Bisconti 2012 (Fig 2) from ten years earlier.
Oversight? Or feud?

Esperante et al 2008 reported,
“This paper documents the exceptional occurrence of thirty seven fossil whale specimens with preserved baleen in the Neogene Pisco Formation during a transect survey in a limited area west of the Ica River Valley near the town of Ocucaje in southern Peru.”

The Pisco Formation runs 15 to 2 mya.
No more specific age estimates were given. Compare to the age estimate for late Miocene Australian Miocaperea at 11-7 mya. Sperm whales were later reported in the Pisco Formation by Benites-Palomino et al 2022, so this was a popular spot for a wide variety.

Figure 3. From Esperante et al 2008, one of 37 whale specimens in Peru with detached baleen structures.

Esperante et al 2008 also wrote,
“Taxonomic identification was not emphasized, although three specimens are cetotheriid-like, and most other whales are balaenopterid-like. The baleen strips were found detached (Fig 3). Esperante et al explained, “This attachment breaks down quickly after death of the individual. This would explain why very few specimens of whale fossils in general have been found with baleen preserved.”

Figure 4. Extant Caperea skull. Here the molars are missing, leaving only alveoli (tooth hole) remnants. See figure 5 for a closeup.

Figure 5. Closeup of the palate of Caperea. Arrows indicate toothless alveoli.

It’s great that so many workers seek
to find the origin of baleen in the mysticete lineage. Add taxa to find this out for yourself. Don’t omit pertinent taxa just because your professor said it would be okay.

Refeences
Benites-Palomino A et al 2022. Sperm whales (Physeteroidea) from the Pisco Formation, Peru, and their trophic role as fat sources for Late Miocene sharks. Proceedings of the Royal Society B online
Bisconti M 2012. Comparative osteology and phylogenetic relationships of Miocaperea pulchra, the first fossil pygmy right whale genus and species (Cetacea, Mysticeti, Neobalaenidae). Zoological Journal of the Linnean Society 166(4) 876—911.
Bisconti M and Carnevale G 2022. Skeletal transformations and the origin of baleen whales (Mammalia, Cetacea, Mysticeti): A study on evolutionary patterns. In: Evolution of Crown Cetacea. A special issue of Diversity ISSN 1424-2818.
Esperante R, Brand L, Nick KE, Poma O and Urbina M 2008. Exceptional occurrence of fossil baleen in shallow marine sediments of the Neogene Pisco Formation, Southern Peru. Palaeogeogr. Palaeoclimatol. Palaeoecol. 257, 344–360. https://doi.org/10.1016/j.palaeo.2007.11.001
Peredo CM, Pyenson ND and Uhen MD 2022. Lateral palatal foramina do not indicate baleen in fossil whales. Nature Scientific Reports 12:11448
Peters D unpublished 2018. The triple origin of whales. ResearchGate.net pdf
Rule JP et al (5 co-authors) 2023. Giant baleen whales emerged from a cold southern cradle. Proceedings of the Royal Society B 290: 20232177 https://doi.org/10.1098/rspb.2023.2177

wiki/Miocaperea
nature.com/articles/nature.2017.21966
https://museumsvictoria.com.au/article/rewriting-whale-evolution/

SVP 2018: Tooth loss in mysticete whales x5 abstracts

Aetiocetus: it’s supposed to be a baleen whale ancestor

A fin whale fetus skull recalls an ancestor with fingers: Behemotops

Mystacodon: See how far they’ll go to ‘find’ a mysticete ancestor

Mystacodon: still NOT the earliest known toothed mysticete

Bisconti and Carnevale 2022 discuss the origin of baleen whales while omitting the ancestors of baleen whales

How extinct odontocetes converged with extinct mysticetes

In the LRT
odontocetes are not related to mystictes. That means Cetacea is an invalid clade, or a junior synonym for Placentalia. No one likes this new hypothesis.

The word ‘whales’ will never leave the dictionary, even though it is now meaningless in a monophyletic sense. And that’s okay for the general public. But these are the sort of things paleontologists need to test for themselves by adding pertinent taxa.

That hasn’t stopped whale workers
from lumping odontocetes with mysticetes in their cladograms. This is completely understandable due to the very impressive convergence between certain members of both clades (Fig 1). If I didn’t know better, I’d be on board, too!

Their problem is taxon exclusion,
plain and simple.

If you omit pertinent outgroup taxa
and focus on just the whale-like taxa themselves, these two taxa (Fig 1) seem to be the most similar due to convergence.

Not sure why I’m doing this. It is a pointless experiment in taxon exclusion. But it may help readers understand the influences today’s whale workers are under – when they omit pertinent taxa. What is academically acceptable and rewarded with publication is the way to go if you’re under the influence of your peers and professors.

Figure 1. Toothless Herpetocetus and toothy Simocetus share a long list of traits, as you can see by the images here. In the LRT, adding taxa separates them. We live in a world of convergence.

The convergence is indeed impressive.
Unfortunately that convergence has only led to confusion and promotion of an outdated myth. Like all cladograms, the LRT lumps related taxa and splits unrelated taxa. Including so many taxa enables the LRT to minimize the traditional taxon exclusion that leads to phylogenetic confusion.

The presented hypothesis requires a competing hypothesis
that includes a similar enough taxon list to confirm, refute or modify the cladogram recovered by the LRT.

Show a little curiosity. Build your own LRT. Add pertinent taxa.

References
Bisconti M and Carnevale G 2022. Skeletal transformations and the origin of baleen whales (Mammalia, Cetacea, Mysticeti): A study on evolutionary patterns. In: Evolution of Crown Cetacea. A special issue of Diversity ISSN 1424-2818.
Peters D unpublished 2018. The triple origin of whales. ResearchGate.net pdf

wiki/Cetacea

The Field Museum announces acquisition of ‘Archaeopteryx 13’

Lumpers seem to like ‘Archaeopteryx‘.
Few workers want to add more than one or two to their analyses. Most want to consider all Solnhofen birds congeneric and conspecific. This is good marketing. Everyone wants an ‘Archaeopteryx‘.

At it turns out, few get them. Most remain in Germany.
So it’s a big deal to the Field Museum when one (Figs 1, 2) comes to Chicago.

Figure 1. The Field Museum Solnhofen bird here with wings re-articulated.

If all these Solnhofen birds are ever added to an academic cladogram
then someone in Chicago will someday realize they don’t have an Archaeopteryx, even though they might have the most primitive Solnhofen bird, the great-grandaddy of all birds. That’s a possibility no one wants to deal with. So they look the other way.

The Chicago (Field Museum) specimen will not enter the LRT until more details are known, but presently (and without scale bars or much attention paid) it reminds me of JM2257 (Fig 3).

In any case, this (Figs 1, 2) is one of the better specimens, even though it’s pectoral girdle popped off during taphonomy. That’s a little strange, considering all the white meat surrounding that area. Lots of wing and tail feather impressions were preserved. Artists have created an animated version of the bones, fleshed out with feathers in the video below.

Figure 2. Closeup of the new Field Museum Solnhofen bird. New preparation techniques are present here. Note the gray egg-shape mass anterior to the femur. No doubt the skull will be µCT scanned for the paper.

From NBCChicago.com
“With feathers and wings, the specimen is believed to be the earliest-known dinosaur that also qualifies as a bird, cementing a link that has lasted for millions of years.”

Journaliststs, please! Don’t use the term ‘believed’. This is science, not religion.
Instead, use the term, “paleontologists have determined.”

“According to the museum, the fossil has the most complete skull of any of the dozen Archaeopteryx specimens found in the world. It features impressions of the creature’s feathers, along with hollow bones, 52 tiny teeth, a long and bony tail, and wings that actually featured clawed hands and movable fingers, according to experts.”

Good job, journalists! “According to experts” is an excellent way of describing what paleontologists are telling you.

Figure 3. Most of the complete Solnhofen birds, including Archaeopteryx and the eleventh specimen to scale. No scale bars were provided for the new Filed Museum specimen, n13.

The LRT was able to
lump and separate nine of the most complete Solnhofen birds (Fig 4). Some nest together. Others don’t. The Thermopolis specimen is the most primitive, of the Solnhofen birds. The Dating specimen is a pre-bird theropod. The holotype London specimen is the most derived, close to Hesperornis, the flightless water bird of the Late Cretaceous of North America. There was a lot of water surrounding the Solnhofen islands in the Late Jurassic.

Figure 4. Subset of the LRT focuscing on Solnhofen birds. many labeled with the wastebasket taxon, Archaeopteryx.

Still waiting for others
to confirm, refute or modify this hypothesis of interrelationships (Fig 4) by simply adding taxa. In paleontology, you have to be patient for someone to get around to doing this.

That’s why I did that several years ago. I was curious.

Figure 5. The Berlin and Chicago specimens compared.

The death pose of the Chicago specimen
greatly resembles that of the Berlin specimen (Fig 5) once the pectoral girdle is replace to its in vivo position. The Chicago specimen has a larger skull and slightly longer hind limbs. We’ll see what the experts determine.

Maybe the addition of the Chicago specimen to a cladogram will prompt workers to add all the other reasonably preserved specimens. Or will they forego this test, opting instead to just call it the Chicago Archaeopteryx?

References
Alonso PD, Milner AC, Ketcham RA, Cookson MJ and Rowe TB 2004. The avian nature of the brain and inner ear of Archaeopteryx Nature 430, 666-669.
Dames W 1884. Ueber Archaeopteryx. Palaeontologische Abhandlungen, 2 (3):119-198.
Foth C, Tischlinger H and Rauhut OWM 2014. New specimen of Archaeopteryx provides insights into the evolution.of pennaceous feathers. Nature 511:79–83.DOI: 10.1038/nature13467
Heller F 1959. Ein dritter Archaeopteryx Fund aus den Solnhofener Plattenkalken von Langenaltheim/Mfr. Erlanger Geologische Abhandlungen, 31: 1-25; Erlangen
von Meyer H 1861. Archaeopteryx litographica (Vogel-Feder) und Pterodactylus von Solenhofen. Neues Jahrbuch für Mineralogie, Geognosie, Geologie und Petrefakten-Kunde. 1861: 678–679.
Owen R 1863. On the Archaeopteryx von Meyer, with a description of the fossil remains of a long-tailed species from the lithographic stone of Solnhofen. Philosophical Transactions of the Royal Society, London 153: 33-47.
Paul G 2002. Dinosaurs of the Air: The Evolution and Loss of Flight in Dinosaurs and Birds. Johns Hopkins University Press. 460 pp.
Wellnhofer P 1974. Das fünfte Skelettexemplar von Archaeopteryx. Palaeontographica Abt. A Vol. 147 S: 168-216.
Zhou Z and Zhang F-C 2004. A Precocial Avian Embryo from the Lower Cretaceous of China. BREVIA Science 22 October 2004: 306 no. 5696 p. 653. DOI: 10.1126/science.1100000. online abstract here

wiki/Archaeopteryx
eptileevolution.com/archaeopteryx.htm

Publicity
Field Museum NBCChicago.com

 

 

 

 

Adding baleen to Desmostylus

In the LRT
Desmostylus (Fig 1) nests at the base of the baleen whales, the clade Mysticeti.

Figure 1. Desmostylus in several views. Hypothetical baleen added in red. Rostrum distortion straightened. Note the ear hole = external auditory meatus (dark yellow)  rising and incorporating into the squamosal (magenta). Note the width of the mandible compared to the hourglass rostrum as in mysticetes shown in figue 2. In palatal view the baleen is spread laterally. In reality the baleen would appear as a series of points, not lines.

Unfortunately
academic whale experts universally agree that mysticetes arose from odontocetes, but that only works by excluding outgroup taxa tested in the LRT.

Here
hypothetical baleen is added to Desmostylus (Fig 1) descending from a toothless micro-ridge inset from the lateral edge of the palate. This is where premaxillary teeth used to be. Note the mandible is wider than the rostrum in Desmostylus as in Caperea and Eubalaena, (Fig 2) two examples of baleen whales.

After testing all competing candidates, this is where and how baleen developed in desmostylians prior to the transformation of fore limbs, the loss of hind limbs and development of flukes.

Figure 2. Taxa in the lineage of right whales include Desmostylus, Caperea and Eubalaena. The tiny bit of jugal posterior to the orbit (in cyan) is found in all baleen whales tested so far. The frontals over the eyes are just roofing the eyeballs in Desmostylus, much wider in Caperea and much, much longer in Eubalaena.

Desmostylus hesperus
(Marsh 1888; Oligocene. Figs 1, 2) was the first desmostylian discovered and is known from several distinct species. One has a relatively larger skull and smaller limbs with a smaller hind limb and thus is transitional to right whales like Caperea and Eubalaena. That specimen also has smaller anterior teeth and narrower jaw tips. Like all mysticetes, the mandible is wider than the rostrum. A complete skeleton is shown to scale with sister taxa (Fig 2).

References
Cope ED 1872. Descriptions of some new Vertebrata from the Bridger Group of the Eocene. Proceedings of the American Philosophical Society 12:460-465.
Domning DP, Ray, CE and McKenna, MC 1986. Two new Oligocene desmostylians and a discussion of Tethytherian systematics. Smithsonian Contributions to Paleobiology. 59. pp. 1–56.
Fordyce RE and Marx FG 2013. The pygmy right whale Caperea marginata: the last of the cetotheres. Proceedings of the Royal Society B: Biological Sciences 280(1753):1–6.
Marsh OC 1888. Notice of a new fossil sirenian, from California. American Journal of Science 25(8):94–96.
Peters D 2018. The triple origin of whales rejected manuscript. Online here.
Reinhart RH 1959. A review of the Sirenia and Desmostylia. University of California Publications in Geological Sciences 36(1):1–146.
Santos G, Parham J and Beatty B 2016. New data on the ontogeny and senescence of Desmostylus (Desmostylia, Mammalia). Journal of Vertebrate Paleontology. doi: 10.1080/02724634.2016.1078344
Tsai C-Hi and Fordyce RE 2015. Ancestor–descendant relationships in evolution: origin of the extant pygmy right whale, Caperea marginata. Biol Lett. 2015 Jan; 11(1): 20140875.

wiki/Caperea
wiki/Desmostylus
https://pterosaurheresies.wordpress.com/?s=baleen&submit=Search

Aetiocetus, Desmostylus and the origin of baleen

Bisconti and Carnevale 2022 discuss the origin of baleen whales while omitting the ancestors of baleen whales