‘When whales walked: Journeys in Deep Time’ from PBS

PBS produced a nearly two hour dive into
various ‘new’ paleo-insights featuring many of paleontology’s rising stars and taxa. They called it, “When whales walked: Journey in Deep Time.” The photography and special effects were excellent. Trailer here.

The first chapter (crocs)
starts in Madagascar caves where Voay, the so-called ‘horned’ crocodile fossils are found (Fig. 1). Dr. Evon Hekkala uses DNA to chart croc evolution. Today only it’s cousin, the Nile crocodile, still lives in Madagascar.  (Surprised that Dr. Chris Brochu (U of Iowa) was not interviewed, since he has done so much work with these crocs.)

Figure 1. Dr. Evon Hekkala shows off a horned crocodile skull found in a Madagascar cave.

Figure 1. Dr. Evon Hekkala shows off a horned crocodile skull found in a Madagascar cave.

Chapter two (pre-crocs)
Dr. Bhart-Anjan Bhullar (Yale) takes us back to the Triassic, “in many ways the Age of Crocodiles”, as he assembles the bones of Poposaurus (Fig. 2). Preview here. Bhullar says, “These animals show us what crocodiles were like at the beginning of their evolution.” That’s close, but not true. Actually Poposaurus was basal to poposaurs and archosaurs (crocs + dinos), so it nests just outside of the croc clade. Junggarsuchus or Pseudhesperosuchus would have made his statement true, but he had Poposaurus in his cabinets at Yale. He also had another specimen, a real Triassic croc.

Figure 1. Revised skull reconstruction for the PEFO specimen. Here the anterior is considered a premaxilla. Those teeth are shaped like triangles, but they are very deeply rooted and exposed very little, which casts doubts on its hypercarnivory.

Figure 2. Revised skull reconstruction for the PEFO specimen. Here the anterior is considered a premaxilla. Those teeth are shaped like triangles, but they are very deeply rooted and exposed very little, which casts doubts on its hypercarnivory.

Continuing….
Bhullar next showed us a tiny ‘sphenosuchian’, nearly complete and nicknamed ‘little foot’ and cf. DromicosuchusYPM VP 57103). Originally it was discovered atop Popoposaurus.

Figure 3. The so-called 'little foot' specimen found with Poposaurus in Utah. YPM-VP-57103

Figure 3. The so-called ‘little foot’ specimen found with Poposaurus in Utah. YPM-VP-57103

Then Bhullar pulled a Larry Martin,
describing unique shared characters, rather than deciding what a croc is after phylogenetic analysis. We looked at YPM-VP-57103 earlier here.

Unfortunately,
Bhullar next held up a Euparkeria fossil and told viewers this specimen does not belong in the ancestry of crocs. That may be correct or incorrect depending on how you read it. According to the large reptile tree (LRT, 1546 taxa) Euparkeria nests so far back in the ancestry of crocs, it is too early to be a crocodylomorph.

Figure 3. YPM VP 057 103 reconstructed using color tracings from figures 1 and 2 in two scales. The smaller one shows the tail attached.

Figure 4. YPM VP 057 103 reconstructed using color tracings from figures 1 and 2 in two scales. The smaller one shows the tail attached.

Chapter three (another croc)
Dr. Diego Pol (AMNH) presented a Jurassic notosuchid with a short snout and  large eyes on the side (not on the top). Pol discussed the variety of crocodylomorphs, but showed very few.

Chapter four (birds)
Dr. Julia Clarke (U of Texas) discussed birds and mentioned, “They can dive so deep into waters that light cannot reach.” Hmmm. Never heard that before. Clarke repeated the tradition based on genomic studies that half the total number of birds are passerines (song birds). By contrast, in the LRT sparrows (genus: Passer) give rise only to hoatzins, parrots and moas.

The PBS narrator noted that birds evolved from dinosaurs, then asked the silly question, “How could something so huge and heavy evolve into something so light?” According to the LRT, dinosaur taxa in the bird lineage were never huge, never heavy. Rather many basal small taxa gave rise to larger taxa—including moas and elephant birds, which are huge and heavy birds, as everyone knows. I just pulled a Larry Martin.

Chapter five (more birds)
Dr. Jacques Gauthier (Yale) said “Deinonychus altered everything we know about dinosaurs and birds” and that’s one of the major embarrassments according to Dr. John Ostrom, Gauthier’s mentor.  Gauthier mentions the first feathers were for warmth. Actually that was secondary. Warmth only happens when lots of feathers spread into a thick coat around the body. Gauthier describes the flight stroke of birds as they lift their forelimbs over the back, which is “very weird for tetrapods.” Gauthier makes no mention of Ken Dial‘s work or the elongation and locking down of the coracoids that enable a flight stroke in pterosaurs and birds.

Chapter six (more birds)
Dr. Jingmai O’Connor (USC, IVPP) describes dinosaurs buried in volcanic ash. Specimens document every stage of the dino–bird transition as they once lived side-by-side. She shows and discusses Caudipteryx, Jeholornis and Confuciusornis. O’Connor said an abbreviated tail evolved many times in dinosaurs and birds. You heard that here first, following a paper on pygostyles by O’Connor.

Chapter seven (more birds)
Dr. Erich Jarvis (The Rockefeller U) studies bird brains, learned behavior, and bird song evolution. The PBS narrator asks, “We all want to know is the bird family tree correct?” Jarvis says, he trusts genes to infer relatedness, and “most people trust DNA.” The LRT shows that “most people” are wrong. Jarvis thinks that “just a handful survived the (Cretaceous) mass extinction: shorebirds. ducks, geese, ostriches, emus.” This quietly omits one of the most highly derived bird clades, penguins in the Paleocene.

Chapter eight (whales)
Dr. Mark Uhen (George Mason U) mentioned that Charles Darwin suggested something like a bear could become a mysticete, then described a history of fossil whale discovery beginning with Basilosaurus, first thought to be a giant sea serpent.

Dr. Philip Gingerich (U Michigan) was highlighted for his discoveries in 1975, but even he made the mistake of assuming whale monophyly and descent from artiodactyls (a primitive deer). The LRT recovers at least two origins for extant whales where tenrecs nest basal to odontocetes and desmostylians nest basal to mysticetes. Gingerich discovered Pakicetus in Pakistan, which was once close to Madagascar, where tenrecs are found today.

At the Museum of Natural History in Paris, Dr. Christian De Muizon shows off the complete reconstruction of the Pakicetus skeleton, surprisingly an ancient relative of modern day whales.

Figure 5. At the Museum of Natural History in Paris, Dr. Christian De Muizon shows off the complete reconstruction of the Pakicetus skeleton, surprisingly an ancient relative of modern day whales.

Chapter nine (more whales)
Dr. Christian De Muizon (Muséum National d’Histoire Naturelle, Paris, Fig. 5) shows off a complete skeleton of Pakicetus, saying, “It looks like a dog with a long snout and webbed feet,” ignoring the fact that it looks more like a big tenrec and tenrecs echolocate.

Dr. Carlos Peredo (George Mason U) says baleen whales and toothed whales had their split early within cetacea (30 mya), in the descendants of Dorudon. By contrast, in the LRT the odontocete/mysticete split was much earlier, in the Jurassic. when tree shrews diversified.

Chapter ten (elephants)
Something about elephant tracks and extinction. Interesting to watch, but not much to comment about.

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Gatesy’s blueprint for whale origins omits foundation taxa

Gatesy et al. 2012
attempted to provide “A phylogenetic blueprint for a modern whale.”

Unfortunately
Gatesy et al. did not realize that whales are diphyletic (or triphyletic). Gatesy et al. failed to include anagalid, elephant shrew and tenrec taxa basal to odontocetes and failed to include desmostylian taxa basal to mysticetes.

Not much else needs to be said.
Taxon exclusion, once again, is the fatal flaw.

References
Gatesy J et al. (7 co-authors) 2012. A phylogenetic blueprint for a modern whale. Molecular Phylogenetics and Evolution. PDF online.

Morenocetus: a small Early Miocene right whale ancestor

Another taxon to consider
in our search for the ancestors of right whales. This one is small enough to have a skull similar in size to that of the earlier (Oligocene) desmostylian, Desmostylus (Fig. 1).

Figure 1. Morenocetus and related right whale skulls, Eubaelana and xx to scale along with the Oligocene ancestor in the LRT, Desmostylus.

Figure 1. Morenocetus and related right whale skulls, Eubaelana and Balaenella, to scale along with the Oligocene ancestor in the LRT, Desmostylus. Note the size of the Morenocetus skull is quite similar to that of the earlier Desmostylus, which already has reduced hind limbs. Only the cranial portion of the Morenocetus skull is known and was shown in Buono et al. 2012. All skull drawings are from Buono et al. 2012. They were set to the same scale here.

Buono et al. 2012 report,
“The earliest recognized balaenid is the early Miocene Morenocetus parvus Cabrera, 1926 from Argentina. M. parvus was originally briefly described from two incomplete crania, a mandible and some cervical vertebrae collected from the lower Miocene Gaiman Formation of Patagonia. Since then it has not been revised, thus remaining a frequently cited yet enigmatic fossil cetacean with great potential for shedding light on the early history of crown Mysticeti. Here we provide a detailed morphological description of this taxon and revisit its phylogenetic position. The phylogenetic analysis recovered the middle Miocene Peripolocetus as the earliest diverging balaenid, and Morenocetus as the sister taxon of all other balaenids.The analysis of cranial and periotic morphology of Morenocetus suggest that some of the specialized morphological traits of modern balaenids were acquired by the early Miocene and have remained essentially unchanged up to the present.”

Figure 1. 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.

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.

Wikipedia reports, from Buono et al. 2012:
“Morenocetus is distinguished from more derived balaenids in the narrow exposure of the squamosal lateral to the exoccipital, a short supraorbital process of the frontal, straight lateral edges of the supraoccipital, and a postorbital process of the frontal oriented posteriorly. It can be distinguished from the only other Miocene balaenid, Peripolocetus in having a dorsoventrally expanded zygomatic process of the squamosal. The body length of Morenocetus is estimated at 17 to 18 feet (5.2 to 5.5 m), and the rostrum is moderately arched dorsoventrally in contrast to crown Balaenidae.”

Buono et al. 2012
did not include nearly toothless desmostylians in their taxon list when they analyzed ‘cetacean’ relationships, but continued the myth of the monophyletic clade ‘Cetacea’ due this taxon exclusion issue.

A paper describing the triple origin of whales
can be accessed here and here.

References
Buono MR, Fernández MS, Cozzuol MA, Cuitiño JI and Fitzgerald EMG 2017. The early Miocene balaenid Morenocetus parvus from Patagonia (Argentina) and the evolution of right whales. PeerJ 5:e4148; DOI 10.7717/peerj.4148
Demere T and Pyenson N 2015. Filling the Miocene ‘Balaenid Gap’ – the previously engimatic Peripolocetus vexillifer Kellogg, 1931 is a stem balaenid (Cetacea: Mysticeti) from the Middle Miocene (Langhian) of California, USA. Journal of Vertebrate Paleontology 35 (Supplement): 115A.
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. doi:10.1111/zoj.12108.

wiki/Peripolocetus
wiki/Morenocetus

 

Llanocetus: not a ‘baleen whale with teeth and gums’

Hailed in the popular press
(see below) as a ‘baleen whale with teeth and gums’, Llanocetus denticrenatus (Mitchell 1989; Fordyce and Marx 2018; 8m in estimated length; 34 mya), nests in the large reptile tree (LRT, 1320 taxa) with archaeocete (toothed) whales, not with mysticetes (baleen whales).

Fordyce and Marx described Llanocetus
from a virtually complete skull (Fig. 1) as “the second oldest mysticete known.” Their phylogenetic analysis nested Llanocetus with Mystacodon, which they describe as “the oldest mysticete,” but earlier the LRT nested it with archaeocete toothed whales, too.

Figure 1. Llanocetus, hailed as a baleen whale with teeth and gums, is just a large archaeocete.

Figure 1. Llanocetus, hailed as a baleen whale with teeth and gums, is just a large archaeocete.

According to Fordyce and Marx, “The broad rostrum has widely spaced teeth marked with dental abrasion and attrition, suggesting biting and occlusal shearing.” Such traits are unexpected in a filter-feeder.

Figure 1. (above) Zygorhiza kochi from George Mason University website, likely captured from Kellogg 1936.

Figure 2. (above) Zygorhiza kochi from George Mason University website, likely captured from Kellogg 1936. To make the jaws fit and teeth occlude the mandible had to be reduced and the cranium had to tilted down posteriorly.

Fordyce and Marx attempt to force-fit their new taxon into the Mysticeti
when they report, “As in extant mysticetes, the palate bears many sulci, commonly interpreted as osteological correlates of baleen. Unexpectedly, these sulci converge on the upper alveoli, suggesting a peri-dental blood supply to well-developed gums, rather than to inter-alveolar racks of baleen. We interpret Llanocetus as a raptorial or suction feeder, revealing that whales evolved gigantism well before the emergence of filter feeding.”

No mention of desmostylians here…

Figure 1. Rorqual evolution from desmostylians, Neoparadoxia, the RBCM specimen of Behemotops, Miocaperea, Eschrichtius and Cetotherium, not to scale.

Figure 3. Rorqual evolution from desmostylians, Neoparadoxia, the RBCM specimen of Behemotops, Miocaperea, Eschrichtius and Cetotherium, not to scale. It is worthwhile noting the similarities shown between Cetotherium and Ilanocetus. Such convergences are the source of Fordyce and Marx’s hypotheses.

Fordyce and Marx conclude in their abstract,
“This scenario differs strikingly from that proposed for odontocetes, whose defining adaptation-echolocation-was present even in their earliest representatives.” 

Unfortunately,
the authorse have no idea that those ‘earliest representatives’ of odontocetes are represented today by tenrecs that also echo-locate and travel in pods, as we learned earlier here.

Once again,
taxon exclusion is to blame for the earlier mistakes. Fordyce and Marx refuse to test desmostylians in their analyses, similar to pterosaur workers who refuse to test tritosaur lepidosaurs, and turtle workers who refuse to test small horned pareiasaurs. That’s why the wide gamut taxon list of the LRT comes in so handy. You don’t have to guess or force-fit any taxa… just let the software and the taxon list do your work for you.

No wonder whale workers are not letting
my papers on whale, turtle and pterosaur origins be published. 

References
Fordyce RE and Marx FG 2018. Gigantism precedes filter feeding in baleen whale evolution. Current Biology 28(10):1670–1676.

wiki/Llanocetus

https://www.techtimes.com/articles/227549/20180512/34-million-year-old-skull-from-antarctica-reveals-baleen-whales-had-teeth-and-gums.htm

SVP 2018: Tooth loss in mysticete whales x5 abstracts

Five SVP abstracts
fumble with the issue of tooth loss preceding the origin of mysticete whales under the invalid assumption that the traditional clade Cetacea is monophyletic. It is not. Whales had two or three (right whales make it three) separate origins, as we learned earlier here.

ABSTRACT 1
Ekdale and Deméré 2018
continue beating a dead horse trying to figure out how Aetiocetus evolved into the clade Mysticeti (Figs. 1-4). In the large reptile tree (LRT, 1038 taxa) mysticetes evolved from desmostylians (Fig. 2-4) while being tested against all prior candidate taxa. Odontocetes evolved from tenrecs, pakicetids and archaeocetids (Fig. 1). Ekdale and Deméré 2018 mistakenly (through taxon exclusion) consider the toothed Aetiocetus a member of the traditional ‘toothed mysticetes’ that they mistakenly think “plays a central role in the debate.”

Figure 5. Subset of the LRT focusing on the tenrec/odontocete clade with several whales added.

Figure 1. Subset of the LRT focusing on the tenrec/odontocete clade with several whales added.

The authors conclude:
“These results provide critical evidence that the lateral palatal foramina in A. weltoni are
homologous with lateral nutrient foramina in extant mysticetes. As such, the lateral nutrient
foramina in A. weltoni provide strong support for the hypothesis that aetiocetids possessed both teeth and some form of baleen.”
 Unfortunately the authors saw what they wanted to see. They never tested tenrecs or desmostylians and so failed to recover the correct phylogenetic framework upon which their work could proceed. Maybe a similar CT scan will find similar nerve and blood vessel patterns in desmostyians. Only testing will reveal what the cladogram indicates.

Figure 1. Subset of the LRT focusing on the mesonyx/mysticete clade showing the split between right whales and all other mysticetes.

Figure 2. Subset of the LRT focusing on the mesonyx/mysticete clade showing the split between right whales and all other mysticetes.

ABSTRACT 2
Gatesy et al. 2018 reassess “phylogenetic studies presented over the past dozen years that have variously reconstructed this complex evolutionary sequence. Early work proposed a step-wise transformation in which toothed mysticetes transitioned via ‘intermediate’ forms with both teeth and baleen to toothless filter feeders. Later studies presented alternative scenarios featuring filtration with teeth instead of baleen, loss of a functional dentition before the evolution of baleen, pure suction feeding, and/or convergent evolution of several key mysticete features. We reanalyzed published cladistic matrices in the context of extensive new molecular data, assessed character support for alternative relationships, and mapped six features related to filter feeding in Mysticeti: presence/absence of 1) teeth, 2) baleen, 3) lateral nutrient foramina on the palate (possible osteological correlates of baleen), 4) a broad rostrum, 5) laterally bowed mandibles, and 6) an unsutured mandibular symphysis.”

All for naught.
They could have and should have run a wide gamut phylogenetic analysis like the LRT which separates the ancestors of odontocetes from the ancestors of mysticetes by a wide phylogenetic distance of intervening taxa (Figs. 1, 2). The ancestors of mysticetes are not to be found among the ancestors of odontocetes. This has been online for two years now.

ABSTRACT 3
Geisler, Beatty and Boessnecker 2018
discuss, to no avail, new specimens of Coronodon havensteini, which they say is the most basal mysticete (in the absence of desmostylians and kin) and the LRT nests at the base of the odontocetes and aetiocetes. Surprisingly, the authors report, these specimens support the hypothesis that Coronodon engaged in macrophagy and filter feeding, and underscores the challenges for reconstructing the behaviors of extinct species based on the limited sample provided by the fossil record.” No they have evidence for macrophagy and they have contrived a scenario for filter feeding. 

Figure 1. Taxa in the lineage of the right whale (Eubalaena) include the pygmy right whale (Caperea) and the desmostylian, Desmostylus.

Figure 3. Taxa in the lineage of the right whale (Eubalaena) include the pygmy right whale (Caperea) and the desmostylian, Desmostylus. You don’t have to look for tooth loss in desmostylians. They already have that trait and so many more.

ABSTRACT 4
Lanzetti, Berta and Ekdale 2018
looked at fetal mysticetes and reported, “We present new evidence on the ontogeny of the minke whale, which develops a dense tissue dorsal to the rostral canal where the tooth buds are either already absent or clearly undergoing resorption. The identity of this tissue should be confirmed by histological analysis, but it may be the first sign of baleen development, as posited by previous studies of these species. Overall, the GM analyses show that the fossils occupy a different morphospace than modern species, possibly indicating that they had specific feeding adaptations not shared by modern mysticetes.”
Clearly they are not looking at desmostylians, which loose most of their teeth in adults.

Figure 1. Rorqual evolution from desmostylians, Neoparadoxia, the RBCM specimen of Behemotops, Miocaperea, Eschrichtius and Cetotherium, not to scale.

Figure 41. Rorqual evolution from desmostylians, Neoparadoxia, the RBCM specimen of Behemotops, Miocaperea, Eschrichtius and Cetotherium, not to scale.

ABSTRACT 5
Peredo 2018
thinks tooth loss precedes the origin of baleen in mysticetes by considering an Early Oligocene specimen from Oregon. In his thinking Peredo, like the authors above, is barking up the wrong tree when he reports, “Although living baleen whales are born without teeth, paleontological and embryological evidence demonstrate that they evolved from toothed ancestors that lacked baleen entirely.” However his specimen might be a desmostylian in the lineage of mysticetes when he reports, “This new material includes a transitional fossil mysticete that lacks both teeth and baleen entirely, demonstrating that tooth loss precedes the origin of baleen in mysticetes.”

A toothy Oregon taxon, Salishicetus, was described by Peredo and Pyenson 2018, who nested it basal to other aetiocetids. They reported, “The description of Salishicetus resolves phylogenetic relationships among aetiocetids, which provides a basis for reconstructing ancestral feeding morphology along the stem leading to crown Mysticeti.”

References
Ekdale EG and Deméré TA 2018. Tooth-to-baleen transition in mysticetes: New CT evidence of vascular structures on the palate of Aetiocetus weltoni (Mysticeti, Cetacea). SVP abstract.
Gatesy et al. (4 co-authors) 2018. Contrasting interpretations of the teeth to baleen transition in mysticete cetaceans. SVP abstract.
Geisler J, Beatty BL and Boessenecker RW 2018. New specimens of Coronodon havensteini provide insights into the transition from raptorial to filter feeding in whales. SVP abstract.
Lanzetti A, Berta A and Ekdale EG 2018. Looking at fossils in a new light: teeth to baleen transition in relation to the ontogeny and phylogeny of baleen whales. SVP abstract.
Peredo CM 2018. From teeth to baleen: Tooth loss precedes the origin of baleen in whales. SVP abstracts.
Peredo CM and Pyenson ND 2018. Salishicetus meadi, a new aetiocetid from the late Oligocene of Washington State and implications for feeding transitions in early mysticete evolution. Royal Society Open Science 5: 172336. http://dx.doi.org/10.1098/rsos.172336

Coronodon: another wannabe mysticete ancestor

Geisler et al. 2017
presented Coronodon as a recent addition to the panoply of toothed whales said to be ancestral to mysticetes. Taxon exclusion is once again the problem. The real ancestors of mysticetes (Fig. 3) are mesonychids, hippos, anthracobunids and desmostylians, as we learned earlier. These taxa were not tested by Geisler et al. 2017.

Figure 1. Coronodon, was originally considered a toothed mysticete, but only in the absence of desmostylians, the real ancestors of mysticetes.

Figure 1. Coronodon, was originally considered a toothed mysticete, but only in the absence of desmostylians, the real ancestors of mysticetes. This taxon lies at the base of Odontoceti and Aetioceti in the LRT.

Coronodon havensteini (Geisler et al., 2017; early Oligocene, 30 mya) was originally and is traditionally considered a mysticete whale, basal to baleen whales like Balaenoptera. With more tested taxa here it nests basal to odontocete whales like Aetiocetus and Physeter. The archaeocete teeth were considered the first stage in filter-feeding. Here they are relics from an archaeocete ancestry. Descendants in both branches (aetiocetes, odontocetes) both have simple peg teeth.

Figure 5. Subset of the LRT focusing on the tenrec/odontocete clade with several whales added.

Figure 2. Subset of the LRT focusing on the tenrec/odontocete clade. Mysticetes have another lineage. Coronodon nests at the base of the Odontoceti, but clearly more transitional taxa are waiting to be discovered.

The LRT ancestors to mysticetes
are shown below:

Figure 1. Rorqual evolution from desmostylians, Neoparadoxia, the RBCM specimen of Behemotops, Miocaperea, Eschrichtius and Cetotherium, not to scale.

Figure 3. Rorqual evolution from desmostylians, Neoparadoxia, the RBCM specimen of Behemotops, Miocaperea, Eschrichtius and Cetotherium, not to scale. Key post-crania is missing here, but the skulls tell the tale.

References
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

wiki/Aetiocetus
wiki/Coronodon

Sitsqwayk: Not a transitional (toothed/baleen) whale

Sitsqwik cornishorum (Peredo and Uhen 2016, Fig. 1) was originally considered a transitional whale linking toothy aetiotheres to toothless mysticetes (but only in the absence of desmostylians).

Figure 1. Sitsqwayk reconstruction over the ghosted image of Cetotherium. 456 cm represents the 'total body length' according to Peredo and Uhen 2016. The rostrum is restored shorter here to match the mandible.

Figure 1. Sitsqwayk reconstruction over the ghosted image of Cetotherium. 456 cm represents the ‘total body length’ according to Peredo and Uhen 2016. Seems too short. The largely restored rostrum is shorter here to match the mandible.

Taxon exclusion issues
Here testing a wider gamut of mysticete ancestor candidates, Sitsqwayk nests between Cetotherium and two other cetotheres,  Yamatocetus and TokarahiaSitsqwayk has a short rostrum, a convex posterior mandible and a relatively large scapula. The total length was reported as 456 cm, which would make it proportionately much shorter than Cetotherium (ghosted Fig. 1), based on a common scapula size.

Figure 2. Subset of the LRT focusing on mysticetes, including Sitsqwayk, and their predecessors.

Figure 2. Subset of the LRT focusing on mysticetes, including Sitsqwayk, and their mesonychid and desmostylian predecessors. Note that hippos are not artiodactyls, contra tradition.

The term chaeomysticeti (see citation below)
refers to the ‘toothless’ mysticetes. Such a clade is only possible if aetiocetes and Mammalodon are considered mysticetes, but they are not in the large reptile tree (LRT, 1201 taxa) where all mysticetes are toothless and they arise from desmostylians. Mammalodon has teeth, but it is basal to desmostylians, which progressively loose their teeth as they transition to baleen.

Going one step further…
current evidence (i.e. the LRT) indicates that mysticetes should be divided between right whales and all other mysticetes, both with desmostylian ancestors with legs.

It only takes the deletion of a few taxa
to nest odontocetes with mysticetes, or to nest mysticetes with odontocetes in the LRT, due to massive convergence in living whales… as you might expect. That’s why taxon exclusion can be such a problem in phylogenetic analysis. (Keyword: ‘taxon exclusion‘ for dozens of examples of this in this blog).

References
Peredo CM and Uhen MD 2016. A new basal chaeomysticete (Mammalia: Cetacea) from the Late Oligocene Pysht Formation of Washington, USA. Papers in Palaeontology. 2 (4): 533–554.

wiki/Cetotherium
wiki/Sitsqwayk