A giant Eocene whale from Ukraine

Davydenko et al. 2021
report the discovery of new giant basilosaurid from Ukraine.

From the abstract:
“The earliest fully aquatic cetaceans arose during the Middle Eocene; however, the earliest stage of their divergence is obscure. Here, we provide a detailed redescription of an unusual early cetacean, “Platyosphys einori”, from the Late Eocene of Ukraine (37.8–35.8 million years ago), with new data on its body size, skeletal microanatomy and suggestions on phylogenetic relationships.”

By contrast, in the large reptile tree (LRT, 1793+ taxa) the earliest stage of ‘their divergence’ (mysticetes and odontocetes) extends back to tiny tree shrews in the Jurassic. Contra public and professional opinion, whale divergence is not obscure. Taxon exclusion hampers the Davydenko et al. study.

Figure 1. Cladogram from Davydenko et al. 2021 showing how they nested Playosphys einori. See figure 2 for their proposed mysticetes (with teeth!)

Figure 1. Cladogram from Davydenko et al. 2021 showing how they nested Playosphys einori. See figure 2 for their proposed mysticetes (with teeth!)

Unfortunately the authors presented an outdated cladogram
that considered the former clade ‘Cetacea’ monophyletic. Their paper perpetuates an invalid hypothesis of interrelationships (Figs. 1,2) that omits the ancestors of mysticetes: desmostylians, anthracubunids, hippos, mesonychids and oreodonts. They also omit the ancestors of pakicetids: tenrecs and anagalids.

Figure 2. Portion of the cladogram from figure 1 enlarged and rotated. Llancetus and kin are not mysticete ancestors when more taxa, like Behemotops, are included in the analysis.

Figure 2. Portion of the cladogram from figure 1 enlarged and rotated. Llancetus and kin are not mysticete ancestors when more taxa, like Behemotops, are included in the analysis.

Sadly,
whale workers continue to perpetuate the myth that whales are monophyletic. That was invalidated several years ago here by simply adding taxa.


References
Davydenko S, Shevchenko T, Ryabokon T. et al. 2021. A Giant Eocene Whale from Ukraine Uncovers Early Cetacean Adaptations to the Fully Aquatic Life. Evol Biol (2021). https://doi.org/10.1007/s11692-020-09524-8

researchgate.net/publication/328388746_The_triple_origin_of_whales

reptileevolution.com/reptile-tree.htm

Overlooked convergence: sharks and whales have a gelatinous snout

Short one today.
The pictures tell the story.

Everyone knows
the snout of the sperm whale is shaped by large sacs of spongy gelatinous material, the spermaceti organ and the melon (Fig. 1).

Figure 1. Sperm whale head diagram showing  the spermaceti organ and the junk (melon) sitting atop the elongate rostrum, as in sharks, more or less.  See figure 2.

Figure 1. Sperm whale head diagram showing the spermaceti organ and the junk (melon) sitting atop the elongate rostrum, as in sharks, more or less. See figure 2.

Shark skulls are not shaped like hydrodynamic bullets.
like the skulls of sturgeons, paddlefish and bony fish. Rather, shark skulls (Fig. 2), like sperm whale skulls, have gelatins that fill the voids and support their bullet-shaped snouts.  Since I didn’t see anything like this when I ‘googled’ it, I thought to add it to mix.

Figure 2. Skull of the dogfish shark, Squalus, superimposed on a graphic of the invivo shark. Yellow areas added to show the extent of the gelatinous material that fills the empty spaces above and below the cartilaginous rostrum (nasal homolog).

Figure 2. Skull of the dogfish shark, Squalus, superimposed on a graphic of the invivo shark. Yellow areas added to show the extent of the gelatinous material that fills the empty spaces above and below the cartilaginous rostrum (nasal homolog).

Yesterday’s post on shark skull cartilage
and the bony homologs one can clearly see by coloring the elements (the now common DGS method) invited a reader’s comments that what I’m doing ‘is the death of science.’ As longtime readers know, I follow the evidence and point out flaws in traditional hypotheses, including instances of taxon omission. That this is necessary points not to the death of science, but to the willingness of someone to test untested hypotheses and taxon lists.

I welcome evidence to the contrary.
I make changes constantly. I follow the evidence, not the textbooks and not the professors, unless the evidence supports them.

Thank you
for your interest in this ongoing online experiment of a life-long learner and heretic.

 

SVP abstracts 18: Palatal foramina and the origin of baleen in mysticetes

Peredo and Pyenson 2020 discuss
the origin of baleen in mysticetes by looking at palatal foramina.

“Baleen whales (mysticetes) filter-feed using specialized keratinous plates, called baleen, to sieve large quantities of prey laden water. Baleen represents a wholly novel integumentary structure, with no apparent homologous structure in any living animal. The origins of baleen, and filter-feeding in whales, have been the topic of much debate. In particular, the lack of osteological correlates for baleen makes it unclear which (if any) stem mysticetes first had keratinous structures for filter feeding.”

The origin of baleen in whales is found in traditionally overlooked nearly toothless desmostylians like Desmostylus (Fig. 2) and Behemotops (Fig. 3), taxa nesting basal to mysticetes in the large reptile tree (LRT, 1751+ taxa; subset Fig. 1).

Figure 3. The oreodont-mesonychid-hippo-desmoystlian-mysticete clade subset of the LRT

Figure 1. The oreodont-mesonychid-hippo-desmoystlian-mysticete clade subset of the LRT

“One potential osteological correlate are palatal foramina and sulci: structures in the roof of the mouth that may vascularize the baleen plates.”

Peredo and Pyenson are “Pulling a Larry Martin” by looking for a few ‘key’ traits rather than running a phylogenetic analysis of all traits without excluding pertinent taxa, such as Desmostylus and Behemotops.

“Palatal foramina are present and well developed in extant and fossil crown mysticetes and are preserved in some stem mysticetes as well. Here, we report the presence of numerous and well-developed palatal foramina in non-filter-feeding cetaceans, including crown and stem odontocetes and in stem cetaceans (so-called archaeocetes).”

Peredo and Pyenson are excluding pertinent taxa.

“Additionally, we observe the presence of palatal foramina in 61 observed species of terrestrial artiodactyls.”

Peredo and Pyenson are excluding pertinent taxa. No artiodactyls are basal to any whales in the LRT. Hippos are not artiodactyls in the LRT. Toothed whales arise from tenrecs and anagalids.

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.

The Peredo and Pyenson abstract continues:
“CT scanning demonstrates consistent internal morphology across all observed palatal foramina, suggesting that the palatal foramina observed in extant mysticetes are homologous to those of terrestrial artiodactyls.”

This sounds like cherry-picking taxa. Perhaps palatal foramina are typical of non-arboreal mammals? What do tenrec and desmostylian foramina look like?

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.

The Peredo and Pyenson abstract continues:
“The presence of palatal foramina in non-filter-feeding whales (odontocetes and archaeocetes) and in terrestrial artiodactyls suggest that the structures are more probably associated with an elaborate gingiva or other oral tissue and are alone not reliable osteological correlates for the presence of baleen in fossils.”

Next time, just add pertinent taxa and run the analysis… then see what turns up. The origin of baleen in whales was answered here in 2016. ResearchGate.net has an unpublished paper to read on the triple origin of whales here.


References
Peredo CM and Pyenson N 2020. Palatal foramina in stem whales and terrestrial artiodactyls obfuscate their potential for inferring baleen in stem mysticetes. SVP abstracts 2020.

wiki/Baleen_whale

SVP abstracts 7: Coombs follows the traditional whale origin myth

Coombs 2020 studied whale skulls
using a traditional, but recently invalidated phylogeny. She did not understand the diphyly of the former clade ‘Cetacea’.

From the Coombs abstract:
“The extant clades of whales, Odontoceti (toothed whales) and Mysticeti (baleen whales), diverged ~39 Ma.”

According to the large reptile tree (LRT, 1749+ taxa) that divergence occurred way back when whale ancestors were still tree shrews. A tiny taxon, Anagale (Fig. 1; Late Cretaceous, 75-71mya) is near their last common ancestor.

Figure 1. We are very fortunate to have several of these basal placental taxa still living with us, as chronologically long-lived taxa. Starting with the extant Didelphis at the base of the Theria, phylogenetic miniaturization gave us the smaller Monodelphis domestics and the even smaller M. sores and M. kunsi, which gave rise to the larger Nandinia at the base of the Carnivora, Tupaia, at the base of the expanded Glires, Ptilocercus at the base of the expanded Archonta, and Maelestes at the base of the tenrecs + whales and the Condylarthra, aka the rest of the mammals.

Figure 1. We are very fortunate to have several of these basal placental taxa still living with us, as chronologically long-lived taxa. Starting with the extant Didelphis at the base of the Theria, phylogenetic miniaturization gave us the smaller Monodelphis domestics and the even smaller M. sores and M. kunsi, which gave rise to the larger Nandinia at the base of the Carnivora, Tupaia, at the base of the expanded Glires, Ptilocercus at the base of the expanded Archonta, and the Condylarthra, aka the rest of the mammals.

Continuing from the Coombs abstract:
“Odontocetes evolved high-frequency echolocation and cranial asymmetry, while mysticetes evolved larger masses and filter feeding.”

Actually odontocete ancestors, represented by extant tenrecs, developed echolocation and cranial asymmetry, by the Paleocene 65mya.

Mysticete ancestors did not develop filter feeding until the Oligocene, 34-23mya at the earliest. Mystacodon (Fig. 2; 36mya) was considered the earliest baleen whale, but this toothy whale nests with the odontocete clade.

FIgure 1. This toothy whale with a tiny pelvis is Mystcodon, originally promoted as the earliest known mysticete (baleen whale).

FIgure 2. This toothy whale with a tiny pelvis is Mystcodon, originally promoted as the earliest known mysticete (baleen whale).

Continuing from the Coombs abstract:
“Despite an excellent fossil record and unique morphology, there has been little quantitative study of shape evolution spanning cetacean diversity.”

Before making that statement, Coombs should add taxa to start with a valid phylogeny, lacking at present. Ancestors to both whale clades (Fig. 3) have been traditionally overlooked due to taxon exclusion.

“To quantify morphological disparity and evolutionary rate in cranial shape and to identify ecological correlates of shape variation across Cetacea, I gathered 3D scans of specimens representing 84 living (72 odontocetes, 12 mysticetes) and 72 Eocene to Pliocene fossil (45 odontocetes, 17 mysticetes, 10 archaeocetes) cetaceans. I then digitized 123 landmarks and 64 curves on these scans and conducted high-dimensional geometric morphometric and macroevolutionary analyses within a phylogenetic framework.”

The Coombs phylogenetic framework is fatally flawed due to taxon exclusion. Adding pertinent taxa will solve this problem.

Figure 4. Subset of the LRT focusing on the odontocetes and their ancestors.

Figure 3. Subset of the LRT focusing on the odontocetes and their ancestors.

Continuing from the Coombs abstract:
“The largest component of cranial variation (PC1 = 39.9%) reflects a posterior shift in the nares and separates odontocete and mysticete modes of cranial telescoping. Rostrum length is the major component of variation on PC2 (20.7%) with dolicocephalic [having a long skull] (e.g., Pontoporia blainvillei) and brachycephalic [having a short skull] (e.g., Kogia sima) crania representing the extremes.”

Figure 3. The oreodont-mesonychid-hippo-desmoystlian-mysticete clade subset of the LRT

Figure 4. The oreodont-mesonychid-hippo-desmoystlian-mysticete clade subset of the LRT

Continuing from the Coombs abstract:
“Cranial asymmetry in archaeocetes is high in the rostrum, squamosal, jugal, and orbit, possibly reflecting preservational deformation. In odontocetes, it is highest in the naso-facial region. Mysticetes show levels of asymmetry similar to terrestrial artiodactyls.”

In other words: essentially no asymmetry. Why? Because mysticetes and odontocetes had different ancestors. Artiodactyls had nothing to do with whales ever since the LRT pulled hippos out of the artiodactyls and into the mesonychids (Fig. 4).

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 5. 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.

Continuing from the Coombs abstract:
“Significant rate shifts in asymmetry are observed in the stem odontocetes Xenorophidae (∼30 Ma), Physeteroidea (∼27 Ma), Squalodelphinidae (~27 Ma), and Monodontidae (~7 Ma). Rapid evolution of both cranial shape and asymmetry in cetaceans occurred in the Middle-Late Oligocene and peaks in the Middle Late Miocene, largely due to subclade-specific diversification of rostrum and facial morphology.”

Coombs’ results, no matter how carefully measured, are incomplete because they are not recovered within a valid phylogenetic context. Add pertinent taxa to resolve this issue.


References
Coombs E 2020. Cranial morphology in whales: A study spanning the evolutionary history and diversity of the Cetacean skull. SVP abstracts 2020.

3x a tiny mammal tail evolved flukes

I found the following results
recovered from the large reptile tree (LRT, 1709+ taxa) to be particularly fascinating given the apparent illogic of developing a robust swimming tail with flukes from an tiny ancestral tail barely able to act as a ‘flap’.

You might remember
earlier we looked at the reversal of teeth in the lineage of odontocetes (toothed whales), reversing step-by-step to a simple cone from the typical complex, multi-cusped molar of a tree shrew.

Likewise in toothed whales, but not exactly correlated,
the tail also experienced a reversal, becoming longer and more robust after derivation from the tiny speck of a tail in tenrec ancestors.

With that introduction
here are the three times the tail has elongated and grown horizontal flukes in placental mammals:

1 – Manatee tail evolution
The terrestrial Moeritherium-like ancestors of today’s aquatic manatees and dugongs had a long torso and tiny tail, distinctly unlike the robust tail with flukes found in today’s Sirenia (Figs. 1–3). Prorastomus (Fig. 2) is a transitional taxon having a more robust tail. Procavia, the living hyrax, has an even smaller tail than these taxa and is more primitive.

Figure 1. Moeritherium skeleton. Note the tiny, slender tail.

Figure 1. Moeritherium skeleton. Note the tiny, slender tail.

 

Figure 1. Prorastomus is a pro-sirenian with legs. All four feet remain unknown.

Figure 2. Prorastomus is a pro-sirenian with legs. All four feet remain unknown.

The splitting in two of ancestrally longer caudal vertebrae (or the increase in caudal number while reducing each caudal vertebral length) appears to be the method employed by evolution to create a longer, more robust tail in manatees and their ancestors.

Figure 2. Dusisiren, a manatee sister has a robust tail and presumably, flukes.

Figure 3. Dusisiren, a manatee sister has a robust tail and presumably, flukes.

2 – Mysticete tail evolution
Neoparadoxia (Fig. 4), a desmostylian ancestor of modern toothless (baleen) whales, likewise had a tiny tail, similar to that of its hippo-like ancestors, useless for propulsion.

Figure 1. GIF animation of the Neoparadoxia (original image from Barnes 2013). It seems illogical that the tiny tail of a desmostylian like this would ever become the giant tail of a mysticete, while the giant hind limbs disappear into the torso, but phylogenetic analysis recovers just such a scenario. Many long-jawed desmostylians are known from cranial material only and these are likely to be those that had large tails and smaller hind limbs.

Figure 4. GIF animation of the Neoparadoxia (original image from Barnes 2013). It seems illogical that the tiny tail of a desmostylian like this would ever become the giant tail of a mysticete, while the giant hind limbs disappear into the torso, but phylogenetic analysis recovers just such a scenario. Many long-jawed desmostylians are known from cranial material only and these are likely to be those that had large tails and smaller hind limbs.

The re-elongation of the tail in mysticete ancestors is not (yet) documented in transitional fossils, which is one factor in keeping this bit of evolution a secret, even from whale experts. Nevertheless, the rest of the anatomy is enough to nest these two former clades together into one clade. Here the number of tail vertebrae does not increase so much as the robust morphology of each one (Figs. 5–7).

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 5. 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.

The apparent length of the tail is enhanced by the disappearance of the hind limbs and the pelvis in mysticetes and other completely aquatic mammals.

Figure 2. Caperea, the pygmy right whale, is a much smaller sister to Eubalaena. Only the skeleton with the ribs angled back fits the stranded in vivo specimen and the skull is a better fit when it is slightly larger.

Figure 6. Caperea, the pygmy right whale, is a much smaller sister to Eubalaena. Only the skeleton with the ribs angled back fits the stranded in vivo specimen and the skull is a better fit when it is slightly larger.

Behemotops and Miocaperera fossils (Fig. 7) do not presently preserve tail vertebrae. These transitional taxa are the ones most likely to transition to reduced legs and a robust tail. It is also apparent that these taxa are ancestral to rorquals, while Desmostylus (Fig. 5) is ancestral to right whales… which means 4x a tiny mammal tail evolved flukes.

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

Figure 7. Rorqual evolution from desmostylians, Neoparadoxia, the RBCM specimen of Behemotops, Miocaperea, Eschrichtius and Cetotherium, not to scale.

3 – Odontocete tail evolution
The elongation of the torso and tail in the ancestors of odontocete (toothed) whales is better preserved in the fossil and extant record.

Figure 2. The short-tailed tenrec, Hemicentetes. Other than size and tail length, this taxon shares a long list of traits with the basal whale, Maiacetus in figure 1.

Figure 8 The short-tailed tenrec, Hemicentetes. Other than size and tail length, this taxon shares a long list of traits with the basal whale, Maiacetus in figure 1.

Here, starting with the tiny tail found in Hemicentetes (Fig. 8), the tail elongates in Indohyus and Leptictidium (Fig. 9) to become the swimming organ used in Pakicetus and fully aquatic toothed whales.

Figure 1. Odontoceti (toothed whale) origin and evolution. Here Anagale, Andrewsarchus, Sinonyx, Hemicentetes, Tenrec Indohyus and Leptictidium precede Pakicetus. Maiacetus and Orcinus are aquatic odontocetes.

Figure 9. Odontoceti (toothed whale) origin and evolution. Here Anagale, Andrewsarchus, Sinonyx, Hemicentetes, Tenrec Indohyus and Leptictidium precede Pakicetus. Maiacetus and Orcinus are aquatic odontocetes.

Since a long, robust tail is already in the gene pool,
a placental mammal can redevelop a long, robust tail from not much of one.


References
.researchgate.net/The_triple_origin_of_whales
wiki/Evolution_of_sirenians

Coombs et al. 2020 re-study odontocete skull asymmetry

Coombs et al. 2020 described odontocete (toothed whale) skull asymmetry
but did not trace it back to its origins in tenrecs (Fig. 1), as we did here two years ago. Without a valid phylogenetic context, the answers they sought evaded the Coombs team.

Nine years ago
whale skull asymmetry was studied by Fahlke et al. 2011, likewise without including tenrecs.

Figure 1. Skull asymmetry in odontocete whales from Fahlke et al. 2011.

Figure 2. Hemicentetes an extant echolocating tenrec, also has a twisted skull, like its descendants, the odontocete whales.

From the Coombs et al. abstract:
“Unlike most mammals, toothed whale (Odontoceti) skulls lack symmetry in the nasal and facial (nasofacial) region. This asymmetry is hypothesised to relate to echolocation, which may have evolved in the earliest diverging odontocetes.”

Earlier. See figure 1.

“Early cetaceans (whales, dolphins, and porpoises) such as archaeocetes, namely the protocetids and basilosaurids, have asymmetric rostra, but it is unclear when nasofacial asymmetry evolved during the transition from archaeocetes to modern whales.”

Earlier. See figure 1.

“Early ancestors of living whales had little cranial asymmetry and likely were not able to echolocate.”

Incorrect conclusion. Add taxa. See figure 1. And see Gould 1965, who described echolocation in tenrecs.

Figure 1. Odontoceti (toothed whale) origin and evolution. Here Anagale, Andrewsarchus, Sinonyx, Hemicentetes, Tenrec Indohyus and Leptictidium precede Pakicetus. Maiacetus and Orcinus are aquatic odontocetes.

Figure 2. Odontoceti (toothed whale) origin and evolution from tree shrews to killer whales. Here Anagale, Andrewsarchus, Sinonyx, Hemicentetes, Tenrec Indohyus and Leptictidium precede Pakicetus. Maiacetus and Orcinus are aquatic odontocetes.

Illustrations like these
(Fig 2) can be extremely helpful for ‘seeing’ evolution take place in a series of micro-evolutionary events. Typical of evolution, several lineages go extinct, while one or a few continue to the present day. Here we are lucky enough to have a few flesh and blood tenrecs at the genesis and several odontocetes to compare. This would make a great PhD project.

Coombs et al. 2020
are still not aware that the traditional clade ‘Cetacea’ is no longer valid because odontocete ‘whales’ arise apart from mysticete ‘whales’ in the large reptile tree. Click the links in this paragraph and in the citations below to get more backstory.


References
Coombs EJ, Clavel J, Park T, Churchill M and Goswami A 2020. BMC Biology 18:86 https://doi.org/10.1186/s12915-020-00805-4
Fahlke JM,  Gingerich PD, Welsh RC and Wood AR. 2011. Cranial asymmetry in Eocene archaeocete whales and the evolution of directional hearing in water. PNAS 108 (35) 14545-14548; https://doi.org/10.1073/pnas.1108927108
Gould E 1965. Evidence for Echolocation in the Tenrecidae of Madagascar
Proceedings of the American Philosophical Society 109 (6): 352-360. online here.

https://www.researchgate.net/publication/328388746_The_triple_origin_of_whales

 

Andrewsiphius enters the LRT outside walking whales, with tenrecs

Updated August 29, 2021
with new data on Andrewsiphius: a photo of the skull (Fig. x), humerus and femur. Note the differences between the bones and the diagram (Fig. 1).

Figure x. Andrewsiphius skull

Figure x. Andrewsiphius skull

This is yet another case
of taxon exclusion and therefore… another excellent subject for a PhD dissertation!

According to Wikipedia,
Andrewsiphius (Fig. 1) is an extinct remingtonocetid early whale known from the Eocene.” 

Figure 1. The reconstructed and restored skull of Andrewsiphius from Theiwissen 2009 and colorized using DGS methods here. Tenrec skull is to scale.

Figure 1. The reconstructed and restored skull of Andrewsiphius from Theiwissen 2009 and colorized using DGS methods here. Tenrec skull is to scale.

Not quite.
In the large reptile tree (LRT, 1695+ taxa, subset Fig. 2), which tests more taxa, Andrewsiphius nests as the proximal outgroup to Pakicetus (Fig. 3), the most primitive known walking whale. Prior studies omitted tenrecs and other basal taxa recovered by the LRT.

Andrewsiphius also nests as the proximal outgroup to extant tenrecs (Figs. 3, 5). So, if Andrewsiphius IS a walking whale, so are living tenrecs.

Andrewsiphius was derived from basal leptictids, like Leptictis.  One of these leptictids is extant, the long-nosed elephant shrew, Rhynchocyon (Fig. 6), ancestor to the misunderstood giant predator, Andrewsarchus.

Figure 2. The nesting of Eocene Andrewsiphius basal to extant tenrecs between leptictids and pakicetids.

Figure 2. Subset of the LRT focusing on Odontoceti and their ancestors. Here is the nesting of Eocene Andrewsiphius basal to extant tenrecs between leptictids and pakicetids.

Figure Y. Taxa added August 29, 2021 and the new data from the skull photo (Fig. x) change things slightly in this subset of the LRT.

Figure Y. Taxa added August 29, 2021 and the new data from the skull photo (Fig. x) change things slightly in this subset of the LRT.

Andrewsiphius sloani (originally Protocetus sp. Salni and Mishra 1972; Thewissen and Bajpal 2009; Eocene 50mya est. 3m) was originally considered an early whale with feet, but here nests basal to smaller tenrecs, in a clade between Leptictis and Pakicetus. The rostrum was long and narrow with molars simplified and premolarized. The orbital notch is quite small, as in other tenrecs. The narrow sagittal crest is distinct from the somewhat broader crania found in living tenrecs, but similar to extinct lepitictids including Andrewsarchus.

Figure 2. Skulls of transitional taxa between tenrecs and Odontoceti (toothed whales). These include Tenrec, Lepticitidium, Pakicetus, Rhodhocetus and Orcinus.

Figure 3. Skulls of transitional taxa between tenrecs and Odontoceti (toothed whales). These include Tenrec, Lepticitidium, Pakicetus, Rhodhocetus and Orcinus.

According to Wikipedia,
Andrewsiphius and Kutchicetus (Fig. 4) share several characteristics not present in other remingtonocetids: an elongated snout that is higher than it is wide; foramina (small holes) on the tip of the snout suggesting the presence of whiskers; eyes located dorsally near the cranial midline, resulting in an appearance of a mammalian crocodile; and a very large sagittal crest overhanging the back of the skull. Other characteristics make them distinct: the second and third upper and lower premolars are double-rooted in Andrewsiphius but single-rooted in Kutchicetus; the large diastemata in the former are absent the latter; and the tail vertebrae are more robust in Andrewsiphius.”

Figure 4. Kutchicetus, a sister to Andrewsiphius.

Figure 4. Kutchicetus, a sister to Andrewsiphius.

Molars go through a massive reversal in odontocetes and their ancestors,
from multi-rooted, multi-cusped back to single-rooted, single-cusped, as in basal reptiles.

Figure 3. Tenrec museum mount.

Figure 5. Tenrec museum mount. The long snout of archaeocete and odontocete whales is already evident here.

Tenrec ecaudatus (Lacépède 1799; extant; common or tailless tenrec; 26-39cm; Fig. 5) is a Madagascar predator that gives birth to as many as 32 young and is able to hibernate for up to 9 months. Gould 1965 found evidence for echolocation in tenrecs.

Figure 7. Rhynchocyon, a living elephant shrew, is a living leptictid.

Figure 6. Rhynchocyon, a living elephant shrew, is a living leptictid.

Rhynchocyon chrysopygus (Peters 1847) is the extanct golden rumped elephant shrew that nests here with the tenrecs, unlike another ‘elephant shrew’, Macroscelides, which nests with tree shrews. In Rhynchocyon the cranium is not expanded, the rotrum is long and the orbit is set posteriorly on the skull. It can run fast on narrow limbs as it spends its day seeking invertebrates in leaf litter.

Previous clades of placentals
(Carnivora, Volitantia, Primates, Glires, Scandentia) are derived from arboreal tree shrews descending from Early Jurassic sisters to arboreal Caluromys. The tenrec-odontocete clade is the most primitive clade of placentals that is terrestrial, as are all that follow except derived members of the Xenarthran (small sloths and anteaters) which exceptionally return to the trees.

I hope this stirs more interest into the tenrec origin of Odontoceti
documented in the paper “Triple Origin of Whales” available online here. It was considered a ‘just so’ story and rejected when originally submitted because it explained everything the experts had missed. The nesting of Andrewsiphius as a large Eocene tenrec supports and cements the current hypothesis of interrelationships recovered by the LRT.

If you know of any earlier iteration of this hypothesis,
let me know so I can promote it.


References
Gould E 1965. Evidence for Echolocation in the Tenrecidae of Madagascar
Proceedings of the American Philosophical Society 109 (6): 352-360. online here.
Sahni A and Mishr VP 1972. A new species of Protocetus (Cetacea) from the Middle Eocene of Kutch, western India. Palaentology 15(3):490–495.
Thewissen JGM and Bajpai S 2009. New skeletal material of Andrewsiphius and Kutchicetus, two Eocene cetaceans from India. Journal of Palaeontology 83(5):635–663.

tenrecs-and-echolocation/

wiki/Leptictis
wiki/Rhynchocyon
wiki/Hemicentetes
wiki/Tenrec
wiki/Andrewsiphius

Mystacodon: still NOT the earliest known toothed mysticete

Muizon, et al.  2019
describe the feeding behavior of Mystacodon selenensis (late Eocene, Fig. 1). They nest Mystacodon as ‘earliest known toothed mysticete’.

If this taxon sounds familiar, it is.
We looked at Mystacodon in February 2018 and nested it in the large reptile tree (LRT, 1505 taxa) as a big pakicetid, between Maiacetus and Llanocetus. These nest at the base of the clade that ultimately produces the toothed whales (odontocetes)… not the baleen whales (mysticetes).

FIgure 1. This toothy whale with a tiny pelvis is Mystcodon, originally promoted as the earliest known mysticete (baleen whale).

FIgure 1. This toothy whale with a tiny pelvis is Mystcodon, originally promoted as the earliest known mysticete (baleen whale).

Mystacodon selenensis (Lambert et al. 2017) was promoted as the earliest mysticete, but it nests with Maiacetus, only larger and with a smaller pelvis.


References
Lambert et al. (seven co-authors) 2017. Earliest Mysticete from the Late Eocene of Peru Sheds New Light on the Origin of Baleen Whales. Current Biology. in press. doi:10.1016/j.cub.2017.04.026.
Muizon C, Bianucci G, Martínez-Cáceres and Lambert O 2019. Mystacodon selenensis, the earliest known toothed mysticete (Cetacea, Mammalia) from the late Eocene of Peru: anatomy, phylogeny, and feeding adaptations. Geodiversitas 41 (11): 401-499. https://doi.org/10.5252/geodiversitas2019v41a11. http://geodiversitas.com/41/11

https://pterosaurheresies.wordpress.com/2018/02/16/mystacodon-see-how-far-theyll-go-to-find-a-mysticete-ancestor/

https://pterosaurheresies.wordpress.com/2018/02/16/mystacodon-see-how-far-theyll-go-to-find-a-mysticete-ancestor/

Hapalodectes: when primates split from dolphins

Back when placental mammals were first diversifying in the Jurassic
they all looked like small arboreal marsupial didelophids, like Caluromys, and small arboreal placental tree shrews, like the extant Ptilocercus and Tupaia. Two distinct specimens, both given the genus name Hapalodectes (Fig. 1), are among these basal placental taxa in the large reptile tree (LRT, 1378 taxa).

The slightly smaller
IVPP V5235 specimen attributed to Hapalodectes (Ting and Li 1987) nests at the base of the primate clade. It had already taken on the appearance of a little basal lemur or adapid (Fig. 1).

Figure 1. Two Hapalodectes specimens. The smaller one nests at the base of the Primates. The larger one nests as the base of the anagalid-tenrec-odontocete clade.

Figure 1. Two Hapalodectes specimens. The smaller one nests at the base of the Primates. The larger one nests as the base of the anagalid-tenrec-odontocete clade.

The slightly larger
IVPP V12385 specimen attributed to Hapalodectes (Ting et al. 2004; Fig. 1) nests at the base of the anagalid-tenrec-odontocete clade and it had already taken on the appearance of a little anagalid or elephant shrew.

Other than size, the differences are subtle:

  1. The basal primate has a postorbital ring. The basal anagalid does not.
  2. The basal primate has three upper molars. The basal anagalid has four.
  3. The basal primate cranium has no crest. The basal anagalid has a nuchal and parasagittal crest.
  4. The basal primate anchors the squamosal further back, with a smaller ectotympanic (middle ear container bones below the cranium). The basal anagalid anchors the squamosal further forward, with a larger ectotympanic (for better hearing).

Hapalodectes hetangensis (Ting and Li 1987; 4.5cm skull length; Paleocene, 55 mya; IVPP V 5235) This skull was originally wrongly applied to the Mesonychidae, but here nests at the base of the primates, including Notharctus.  Note the transverse premaxilla, the large canine, and the encircled orbits rotated anteriorly.

?Hapalodectes ?hetangensis (Ting et al. 2004; 7 cm skull length; Early Eocene 50 mya; IVPP V 12385) was originally considered a tiny mesonychid. This species nests at the base of the anagale-tenrec-odontocete clade, between Ptilocercus and Onychodectes. The large nuchal crest is a key trait found in later taxa. The premaxilla is largely missing, but likely was transverse in orientation.

Figure 2. Ptilocercus (pen-tailed tree shrew) compared to Caluromys (wooly-opossum) young juvenile from Flores, Abdala and Giannini 2010.

Figure 2. Ptilocercus (pen-tailed tree shrew) compared to Caluromys (wooly-opossum) young juvenile from Flores, Abdala and Giannini 2010.

References
Ting S and Li C 1987. The skull of Hapalodectes (?Acreodi, Mammalia), with notes on some Chinese Paleocene mesonychids.
Ting SY, Wang Y, Schiebout JA, Koch PL, Clyde WC, Bowen GJ and Wang Y 2004. New Early Eocene mammalian fossils from the Hengyang Basin, Hunan China. Bulletin of Carnegie Museum of Natural History 36: 291-301.

wiki/Hapalodectes

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.