Flying squirrels and aye-ayes: convergent with multituberculates

For those in a hurry, a two-part summary:
1. By convergence, basal multituberculates in the Jurassic (Figs. 1, 4), had a distinct  flying squirrel (Glaucomys, Figs. 2, 3)-like patagial (= gliding membrane) morphology.
2. Also by convergence, multituberculates in the Jurassic had a short post-dentary skull length with a sliding jaw joint and a nearly absent angular process as seen in the extant aye-aye (Daubentonia, Figs. 5, 6).

Figure 2. The paratype specimen of Arboroharamiya HG-M018, in situ. DGS color tracing added. The skull is in poor shape.

Figure 1. The paratype specimen of Arboroharamiya HG-M018, in situ. DGS color tracing added. The skull is in poor shape.

Today’s blogpost had its genesis
when I finally noticed several basal multituberculates that preserved soft tissue had flying-squirrel-like patagia preserved in the sediment (Fig. 1)… and squirrels nested more or less close to the origin of multituberculates. So, I added a flying squirrel, Glaucomys (Fig. 1) to the large reptile tree (LRT, 1810+ taxa) to see what would happen.

It should come as no surprise
that Glaucomys nested with the extant red squirrel Sciurus, NOT any closer to multituberculates. Thus, the ability to glide in the manner of a flying squirrel turned out to be by convergence in basal multituberculates of the Jurassic.

Figure 2. Glaucomys gliding.

Figure 2. Glaucomys gliding.

Figure 2. Multituberculates to scale. Carpolestes is the proximal outgroup taxon.

Figure 3. Multituberculates to scale. Carpolestes is the proximal outgroup taxon.

Based on the phylogenetic position
of squirrels and other rodents as sisters to multituberculates, either flying squirrels were also gliding from tree-to-tree during the Mesozoic, or they took their time and only appeared after the Mesozoic. That is the current paradigm based on present evidence.

End of part 1. Scroll down for part 2.

Figure 1. Subset of the LRT focusing on basal placentals, including multituberculates.

Figure 4. Subset of the LRT focusing on basal placentals, including multituberculates.

Part 2.
By convergence, the aye-aye, Daubentonia

(Fig. 5) has a multituberculate-like mandible lacking an angular process along with a large circumference, sliding jaw joint and reduced post-dentary skull.

Figure 1. Taxa in the lineage of Daubentonia and multituberculates.

Figure 5. Taxa in the lineage of Daubentonia and multituberculates. Note the loss of the angular process and the sliding jaw joint.

By convergence, Carpolestes
has an enlarged posterior lower premolar, as in multituberculates. So, lots of convergence surrounds the multituberculates.

The aye-aye is a traditional basal primate,
based on gene studies (Dene et al1980; Rurnpler et al 1988; Del Pero et al 1995; Porter et al 1995).

By contrast
the large reptile tree (LRT, 1810+ taxa; subset Fig. 4) nests the aye-aye (Daubentonia) with rodents, plesiadapiformes, carpolestids and multituberculates. We’ve seen how genomic studies produce false positives. Add Daubentonia to that list of flubs. Note that both lemurs and aye-ayes are both from Madagascar, lending more evidence to the hypothesis that geography and geology (e.g. Afrotheria, Laurasiatheria) affect genomics to a greater degree than professionally realized over deep time.

Like rodents:
The aye-aye does not have mammary glands on the chest, as in primates, but along the groin, as in non-primates. The aye-aye has a large diastema between the incisors and molars, as in plesiadapiformes and rodents, distinct from primates.

Like primates:
The aye-aye has a postorbital bar, stereoscopic vision and an opposable hallux. Owen 1863 considered such traits ‘must be ordained’ in arguments for God and against Darwin’s then novel hypothesis of natural selection and evolution.

Like rodents,
Perry et al. 2014 report: “the single pair of incisors consists of continuously growing, elongate, open-rooted chisels, both upper and lower incisors.”

Based on the LRT
mutltuberculates are netonous rodents, growing to adulthood without ontogenetically incorporating post-dentary bones into the tympanic and periotic (inner ear enclosing bones), as we learned earlier here.

Figure 6. The aye-aye, Daubentonia in vivo. This is the closest living relative of multituberculates and is itself a plesiadapiform member of Glires, close to rodents, not primates.

Figure 6. The aye-aye, Daubentonia in vivo. This is the closest living relative of multituberculates and is itself a plesiadapiform member of Glires, close to rodents, not primates.

By convergence
the aye-aye (Daubentonia. Fig. 6) likewise reduces the tympanic and periotic along with the angular process of the dentary, producing a sliding joint that would have interfered with the ear bones if allowed to develop as in most placentals.

Carter 2009 notes
(while mistakenly assuming a lemur affinity for Daubentonia), “The overall dimensions of the D. madagascariensis auditory ossicles are large and they have a unique morphology.” Carter also reports on the elongate manubrium of the malleus (the former articular). This is in accord with similar structures in the neotonous (not primitive!) multituberculate auditory bone chain you can see here.

What does the angular process of the plancental dentary do?
According to Meng et al. 2003, a huge angular process was present in Rhombomylus, an extinct gerbil. Meng et al. mapped insertions for the deep masseter and superficial masseter externally. Then they mapped insertions for the medial pterygoid and superficial masseter internally. The Rhomboylus glenoid has a small diameter and rotates. It does not slide.

Meng et al. write: “As the major muscle to move the mandible forward, the superficial masseter must be long enough so that it can work to bring the jaw forward at least the minimum working distance. In general, the action line of the anterior deep masseter is nearly perpendicular to the moment arm of the mandible, while the posterior one has an acute angle to the moment arm and, therefore, less mechanical advantage. the deep masseter must have been sizable and supplies the main force for mastication as in rodents.”

The point of which is: multituberculates and the aye-aye reduce and eliminate the angular process. So we can imagine the muscles listed by Meng et al. either migrate or are lost in multituberculates and the aye-aye.

Figure 1. Maiopatagium in situ in white and UV light. The X marks an area surrounded by fur lacking proptagial data. Is the propatagium wishful thinking?

Figure 7. Maiopatagium in situ in white and UV light. The X marks an area surrounded by fur lacking proptagial data. Is the propatagium wishful thinking? Yes. Those are long guard hairs, precursors to porcupine quills. There is no patagium here.

We can’t leave Jurassic flying squirrels
without a quick review of Maiopatagium (Early Jurassic, Fig. 7, Meng et al. 2017), which was hailed ever since as a gliding mammal or mammaliaform.

Contra Meng et al. 2017
phylogenetic analysis nested Maiopatagium with the extant porcupine (Coendou), not with gliding multituberculates, like Vilevolodon. Maiopatagium has long straight hairs and lacks any trace of a patagium. Those long straight hairs are the precursors to porcupine quills according to the LRT.

Phyogenetic analysis puts rodents and all their precursors
(Tupaia, Henkelotherium, Nasua) squarely and clearly in the earlier part of the Early Jurassic, though not yet recovered in fossils.

The myth about the patagium surrounding Maiopatagium
seems to have had its genesis in the fact that Vilevolodon was described at the same time,  by the same authors, in the same publication. Vilevolodon (Fig. 1) has a no-doubt, flying sqirrel-like patagium. Maiopatagium (Fig. 7) was described with a misidentified patagium and a misidentified bat-like calcar. No patagium is present, but long straight hairs are. As noted above, these are precursors to porcupine quills. Getting taxa into a proper phylogenetic context is the key to understanding soft tissue and taxonomy.


References
Carter Y 2009. Monkey Hear: A morphometric analysis of the primate auditory ossicles. Master of Arts thesis, The U of Manitoba.
Del Pero M et al (4 co-authors) 1995. Phylogenetic relationships among Malagasy lemuls as revealed by mitochrondrial DNA sequence analysis. Primates 36: 43I-440.
Dene H, Goodman M and Prychodlco V 1980. Immunodiffusion systematics of the primates. Mamalia 44:27-31.
Luo Z-X, (6-co-authors) 2017. New evidence for mammaliaform ear evolution and feeding adaptation in a Jurassic ecosystem. Nature. in press (7667): 326–329. doi:10.1038/nature23483
Meng et al. 2003. The osteology of Rhombomylus (Mammalia, Glires): Implications for phylogeny and evolution of Glires. Bulletin of the American Museum of Natural History 275: 1–247.
Meng Q-J, Grossnickle DM, Liu D, Zhang Y-G, Neander AI, Ji Q and Luo Z-X 2017.
New gliding mammaliaforms from the Jurassic. Nature (advance online publication)
doi:10.1038/nature23476
Owen R 1863. On the characters of the aye-aye as a test of the Lamarckian and Darwmian hypothesis of the transmutation and origin of the species. Rep Br Assoc Adv Sci 1863: 114-116.
Perry JM et al. (4 co-authors) 2014. Anatomy and adaptations of the chewing muscles in Daubentonia (Lermuriformes). The Anatomical Record 297:308–316.
Porter CA et al (5 co-authors) 1995. Evidence on primate phylogeny from e-globin gene sequences and flanking regions. Journal of Molecular Evolution 40: 30-55.
Rurnpler Y et al (4 co-authors) 1988. Chromosomal evolution of the Malagasy lemurs. Folio Primatologica 50 124-129.
Sterling EJ 1994. Taxonomy and distribution of Daubentonia madagascariensis: a historical perspective. Folio Primatologica 62: 8-I3.

wiki/Maiopatagium
wiki/Coendou
wiki/Multituberculata

https://pterosaurheresies.wordpress.com/2019/01/06/a-post-dentary-reversal-between-rodents-and-multituberculates/

Purgatorius and Plesiadapis are still not primates contra Wilson et al. 2021

Short one today
on Purgatorius (Early Paleocene; Fig. 1), a mandible taxon considered by Wilson et al. 2021 to be a member of the Plesiadapiformes (Fig. x).

Figure 1. Purgatorius compared to other basal and often Paleocene mammals.

Figure 1. Purgatorius compared to other basal and often Paleocene mammals.

Wilson et all 2021 report
“Plesiadapiforms are crucial to understanding the evolutionary and ecological origins of primates and other euarchontans (treeshrews and colugos) as well as the traits that separate those groups from other mammals.”

No they are not.

Adding taxa
shifts plesiadapiformes deep into the clade Glires (Fig. x) where Plesiadapis joins Daubentonia as primate-like rodents close to Carpolestes and Ignacius.

Figure 1. Ignacius and Plesiadapis nest basal to Daubentonia in the LRT.

Figure 2. Ignacius and Plesiadapis nest basal to Daubentonia in the LRT.

Wilson et al. also reported
similarities in Purgatorius to Palaechthon, which nested in 2017 with the demopteran, Cynocelphalus in the large reptile tree (LRT, 1807+ taxa). Wilson et al. considered Palaechthon a member of the Plesiadapiformes.

Figure 1. Subset of the LRT focusing on basal placentals, including multituberculates.

Figure x. Subset of the LRT focusing on basal placentals, including multituberculates.

We looked at Purgatorius earlier
here in 2017.

Colleagues, expand your taxon lists.
If you don’t look in there, you won’t see what’s in there. So look. Add taxa. Sometimes traditions, professors and textbooks are not complete or incorrect. Find out for yourself.


References
Wilson MGP et al. , (9 co-aiuthors) 2021. Earliest Palaeocene purgatoriids and the initial radiation of stem primates Royal Society open science 8210050
http://doi.org/10.1098/rsos.210050

https://pterosaurheresies.wordpress.com/2019/03/07/tweaking-palaechthon-basal-volitantia/

The coatimundi (Nasua) enters the LRT basal to almost all placentals

Traditionally
the coatimundi (Nasua nasua (Figs. 1, 3, 4; originally Viverra nasua Linneaus 1766) is considered a close relative of the raccoon (Procyon), a member of the Carnivora. So it has not gotten the spotlight it deserves.

Figure 1. The coatimundi (Nasua) compared to the ring-tailed lemur (Lemur).

Figure 1. The coatimundi (Nasua) compared to the ring-tailed lemur (Lemur).

By contrast, 
here in the large reptile tree (LRT, 1804+ taxa, Fig. x) Nasua nests outside the Carnivora, alongside Protictis, a Middle Paleocene taxon, and former enigma.

This nesting in the LRT
means the resemblance between coatimumndis and primitive carnivores, like Procyon, primitive primates, like Lemur (Fig. 1), and primitive tree shrews like Tupaia and Ptilocercus, is not mere convergence, but homology.

Overlooked until now,
coatimundis are basal to virtually all placental mammals, including primates and humans. That’s why they look like lemurs. That’s why they look like big tree shrews. That’s why they look like the LRT ancestor of bats, Chriacus, already with those large claws and feet able to rotate 180º enabling head-down descent from trees.

And that’s not all.
Coatimundis also dig with those big claws. So it is no coincidence that Talpa, the mole, is only a few nodes deep in the base of the Carnivora.

It is also worthwhile to compare
Nasua to an outgroup taxon, Caluromys (Fig. 4), an arboreal marsupial close to the base of the Placentalia.

Figure x. Subset of the LRT focusing on Carnivora and basal Placentalia after the addition of Nasua.

Figure x. Subset of the LRT focusing on Carnivora and basal Placentalia after the addition of Nasua. This phenomic cladogram is very different from genomic cladograms you may have seen, some that employ tapirs for outgroups.

Distinct from all members of the Carnivora
in the LRT, Nasua retains three large molars and a vestigial fourth along with a long list of other more subtle traits. Members of the Carnivora have only two molars typically with a large carnassial tooth preceding the upper molars.

Figure 2. Skull of Nasua compared to mid-Paleocene Protictis. The two are a close match and nest together in the LRT.

Figure 2. Skull of Nasua compared to mid-Paleocene Protictis. The two are a close match and nest together in the LRT. Shown about three-fifths life size.

According to Wikipedia
“Adult coatis measure 33 to 69 cm (13 to 27 in) from head to the base of the tail, which can be as long as their bodies. Males can become almost twice as large as females and have large, sharp canine teeth.Coatis have non retractable claws for climbing and digging. They prefer to sleep or rest in elevated places and niches, like the rainforest canopy, in crudely built sleeping nests. Coatis are active day and night but are not nocturnal animals. In the wild, coatis live for about seven years, while in captivity they can live for up to 15 or 16 years. Coatis communicate their intentions or moods with chirping, snorting, or grunting sounds. The pregnant females separate from the group, build a nest on a tree or in a rocky niche and, after a gestation period of about 11 weeks, give birth to litters of three to seven kits. About six weeks after birth, the females and their young will rejoin the band. Females become sexually mature at two years of age, while males will acquire sexual maturity at three years of age.”

The tail is not prehensile, but is used for balance.
Coatis able to rotate their ankles beyond 180°; they are therefore able to descend trees head first.

Figure 3. Skeleton of the coatimundi (Nasua) along with images of the hands, feet, antebrachium and humerus.

Figure 3. Skeleton of the coatimundi (Nasua) along with images of the hands, feet, antebrachium and humerus.

Although Middle Paleocene Protictis
(Fig. 2). nests alongside Nasua, they both had their origin deep in the Jurassic based on Jurassic remains of more derived taxa among the multituberculates. So the coatimundi was a friend, a meal, or at least an observer, of dinosaurs. This genus is a previously overlooked living relative of human ancestors, much more than the agricultural pest some people think.

Figure 1. Mammals at the base of the Placentalia include the outgroup taxon: Caluromys, a basal placental: Genetta, a basal Carnivora: Eupleres, a basal Volitantia: Ptilocercus, a basal Primates: Microcebus, and basal Glires: Tupaia.

Figure 4. Mammals at the base of the Placentalia include the outgroup taxon: Caluromys, a basal placental: Genetta, a basal Carnivora: Eupleres, a basal Volitantia: Ptilocercus, a basal Primates: Microcebus, and basal Glires: Tupaia.

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


References
Linneaus C 1766. Systema naturae : per regna tria natura, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. 1 (12 ed.). Holmiae: L. Salvii.
wiki/Coati
wiki/South_American_coati

 

 

 

Carnivora genomic testing: Hassanin et al. 2021

From the abstract:
“The order Carnivora, which currently includes 296 species classified into 16 families, is distributed across all continents. The phylogeny and the timing of diversification of members of the order are still a matter of debate. Here, complete mitochondrial genomes were analysed to reconstruct the phylogenetic relationships and to estimate divergence times among species of Carnivora.”

Genomic tests too often do not and can not test fossil taxa leading to a problem with taxon exclusion. Moreover, genomic testing in deep time too often delivers false positives relative to phenomic (trait-based) traits that are designed to produce tree topologies in which all sister taxa greatly resemble one another, modeling micro-evolutionary events. Why this is so remains an unsolved problem. A phenomic cladogram (the LRT, subset Fig. x) that includes fossil taxa is found online here: http://reptileevolution.com/reptile-tree.htm

Figure 2. Talpa the Eastern mole nests in the LRT with Herpestes the mongoose.

Figure 1. Talpa the Eastern mole nests in the LRT with Herpestes the mongoose.

Talpa, the mole (Fig. 1), was excluded here, but nests within Carnivora in the phenomic analysis, the large reptile tree (LRT, 1803+ taxa, subset Fig. x).

Figure 1. Nandinia, the palm civet, nests as the proximal outgroup taxon to the Carnivora and all other placental mammals.

Figure 2 Nandinia, the palm civet, nests as the proximal outgroup taxon to the Carnivora and all other placental mammals.

Nandinia, the palm civet sure looks like it, but is not a basal member of Carnivora in the LRT, but a basal placental outgroup taxon to the clade Carnivora.

Figure 1. Mammals at the base of the Placentalia include the outgroup taxon: Caluromys, a basal placental: Genetta, a basal Carnivora: Eupleres, a basal Volitantia: Ptilocercus, a basal Primates: Microcebus, and basal Glires: Tupaia.

Figure 3. Mammals at the base of the Placentalia include the outgroup taxon: Caluromys, a basal placental: Genetta, a basal Carnivora: Eupleres, a basal Volitantia: Ptilocercus, a basal Primates: Microcebus, and basal Glires: Tupaia.

Carnivora is the first major clade to split off
from basal Placentalia (Fig. x). Therefore, the proximal outgroup taxon, the woolly oppossum, Caluromys (Fig. 3) , should be included as the outgroup next time.

Figure 2. Subset of the LRT focusing on the Carnivora.

Figure x. Subset of the LRT focusing on the Carnivora.

By chilling contrast,
in the Hassanin et al. 2021 genomic analysis, a hoofed placental, the tapir (Tapirus), was used as the outgroup taxon. Given all other placentals for their choice of outgroup for Carnivora, why did they choose a relative of horses and rhinos? We’ve seen this sort of confused mayhem before and recently in genomic studies. Let’s all pray that the ghost of Alfred Sherwood Romer will come visit Hassanin et al. and all others who think this is a good idea.


References
Hassanin A, Veron G, Ropiquet A, Jansen van Vuuren B, Le´cu A, Goodman SM, et al. 2021. Evolutionary history of Carnivora (Mammalia, Laurasiatheria) inferred from mitochondrial genomes. PLoS ONE 16(2): e0240770. https://doi.
org/10.1371/journal.pone.0240770

Macrauchenia: the good and bad of genomic studies

From the Wesbury et al. 2021 abstract
“The unusual mix of morphological traits displayed by extinct South American native ungulates (SANUs) confounded both Charles Darwin, who first discovered them, and Richard Owen, who tried to resolve their relationships. Here we report an almost complete mitochondrial genome for the litoptern Macrauchenia (Fig. 1). Our dated phylogenetic tree (Fig. 2) places Macrauchenia as sister to Perissodactyla, but close to the radiation of major lineages within Laurasiatheria. This position is consistent with a divergence estimate of B66Ma.”

Note they don’t ask us to pay as much attention to the proximal outgroup for Macrauchenia: the clade Carnivora (Fig. 2).

Figure 1. Macrauchenia museum mount.

Figure 1. Macrauchenia museum mount.

According to Wikipedia
Laurasiatheria is a gene-based clade “that includes that includes hedgehogs, even-toed ungulates, whales, bats, odd-toed ungulates, pangolins, and carnivorans, among others.”

Isn’t that an odd assemblage? 
Think about it. According to Wesley et al. (Fig. 2), sabertooth cats are closer to horses, rhinos and Macrauchenia than other long-legged, placental herbivores. By the way, in gene studies elephants appear in an unrelated major clade, Afrotheria.

Figure 1. Gene-based cladogram from Westbury et al. 2021 (slightly compressed to fit). Note the close relationship between Carnivora and Macrauchenia here. That is not replicated in a trait-based study (Fig. 2).

Figure 2. Gene-based cladogram from Westbury et al. 2021 (slightly compressed to fit). Note the close relationship between Carnivora and Macrauchenia here. That is not replicated in a trait-based study (Fig. 2).

A more reasonable, trait-based, phylogenetic analysis
(the large reptile tree, LRT, 1794+ taxa, subset Fig. 3) also nests the Macrauchenia clade basal to tapirs, rhinos and horses. The outgroup is the hyrax + elephant + manatee clade, then the artiodactyls, then the mesonychids + hippos + desmostylians + mysticetes. Off this chart (Fig. 3), the clade Carnivora is the basalmost placental clade, not the proximal outgroup to Macrauchenia.

Figure 2. Subset of the LRT focusing on derived placentals. Yellow highlights the Macrauchenia clade.

Figure 3. Subset of the LRT focusing on derived placentals. Yellow highlights the Macrauchenia clade.

Perhaps taxon exclusion is at fault here.
On the other hand, gene studies too often produce such odd interrelationships (Carnivora nesting closer to Macrauchenia than other herbivore clades). Gene studies too often deliver false positives in deep time studies. That’s a fact, not a hypothesis.

If your professor is asking you to help out on a deep time genomic study,
run.


References
Westbury M et al. (21 co-authors) 2021. A mitogenomic timetree for Darwin’s enigmatic South American mammal Macrauchenia patachonica. Nature Communications | 8:15951 | DOI: 10.1038/ncomms15951 |www.nature.com/naturecommunications

https://en.wikipedia.org/wiki/Laurasiatheria
reptileevolution.com/macrauchenia.htm

Rostriamynodon: ancestor to elephants + manatees, not a perissodactyl

Holbrook 1999
added Rostriamynodon (AMNH 107635, Fig. 1) to his study on perissodactyls (Fig. 3) following work by Wall and Manning 1986 who thought Rostriamynodon was a basal rhino close to Amynodon, which nests basal to horses in the large reptile tree (LRT, 1763 taxa; subset Fig. 2).

Figure 1. Rostriamynodon skull in three views, colors added.

Figure 1. Rostriamynodon skull in three views, colors added.

So, a bit of a taxonomic mess here.
Taxon exclusion is once again the problem. In the LRT (subset Fig. 2) Rostriamynodon nests between the traditional ‘notoungulate’ Notostylops and the elephant (Fig. 5) + manatee (Fig. 6) clade.

Figure 2. Subset of the LRT focusing on ungulates sans artiodactyls.

Figure 2. Subset of the LRT focusing on ungulates sans artiodactyls.

Figure 3. Cladogram from Holbrook 1999 with LRT colors added. Taxon exclusion mars this cladogram.

Figure 3. Cladogram from Holbrook 1999 with LRT colors added. Taxon exclusion mars this cladogram.

Isectolophus was also added to the LRT,
(subset Fig. 2) and it nested uncontroversially basal to Protapirus in the tapir clade in both competing studies.

Taxa in this blogpost:
Amynodon advenus (Marsh 1877; 1m in length; Oligocene-Eocene, 40-23 mya) was originally considered an aquatic rhino. Here it nests with Mesohippus. The long neck and other traits are more horse-like than rhino-like. Manual digit 5 was retained. The skull was deeper as in basal forms like Hyracotherium.

Isectolophus scotti (Scott and Osborn 1887; Early Oligocene to Early Miocene) nests basal to Protapirus in the large reptile tree.

Figure 1. Notostylops skull colorized in three views.

Figure 4. Notostylops skull colorized in three views.

Notostylops murinis (Ameghino 1897, Riggs and Patterson 1935; 75cm in esitmated length; Eocene; FMNH-P13319; Fig. 4) is widely considered a ‘notoungulate’ a clade that has been split into several parts in the large reptile tree. Here it nests with the above specimen of Ectocion in the clade of elephants, rock hyraxes and sea cows. The jaws narrowed anteriorly. The anterior incisors were enlarged, like those of rodents. The mandible was more robust. No canines were present. The premolars were molarized

Rostriamynodon grangeri (Wall and Manning 1986; AMNH 107635; Eocene) was originally considered amynodontid rhino, but here nests between Notostylops and the elephant + siren clade. Note the splitting of the nasals and the anterior extension of the frontals along with the wide molars and the molarized premolars.

 

Figure 2. Skull of Elephas maximus with color overlays. Most of the bones are fused to one another, so this tracing is provisional, pending confirmation and/or better data. Compare to the skull of Procavis (Fig. 3).

Figure 5. Skull of Elephas maximus with color overlays. Note the separation of the nasals.

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

Figure 6. Dusisiren, a manatee sister has a robust tail and presumably, flukes. Note the separation of the nasals, first seen in Rostriamynodon.

References
Hollbrook LT 1999. The phylogeny and classification of Tapiromorph perissodactyls (Mammalia). Cladistics 15:331–350.
Holbrook LT, Lucas SG and Emry RJ 2004. Skulls of the Eocene perissodactyls (Mammalia) Homolgalax and Isectolophus. Journal of Vertebrate Paleontology 24(4):951–956.
Scott WB and Osborn HF 1887. Preliminary Report on the Vertebrate Fossils of the Uinta Formation, Collected by the Princeton Expedition of 1886. Proceedings of the American Philosophical Society 24(126):255-264.
Wall WP and Manning E 1986. Rostriamynodon grangeri n. gen., n. sp. of amynodontid (Perissodactyla, Rhinocerotoidea) with comments on the phylogenetic history of Eocene Amynodontidae. Journal of Paleontology 60(4):911-919.

wiki/Notostylops
wiki/Rostriamynodon not yet posted
wiki/Protapirus
wiki/Isectolophus not yet posted

 

Chilecebus: Oldest South American monkey

Flynn et al. 1995 brought us
Chilecebus carrascoensis (Early Miocene; 20mya; Fig. 1 lower left) a tiny New World monkey from Early Miocene Chile.

Figure 1. Chilcebus compared to other Western Hemisphere primates.

Figure 1. Chilcebus compared to other Western Hemisphere primates. Note the three molars in Chilecebus, as in Smilodectes and Aotus, not Alouatta. Dorsal view and CT scan view of Chilecebus on second of two frames.

When added to
the large reptile tree (LRT, 1753+ taxa) Chilecebus nested with the other South American monkeys.

Figure 1. At the start of the Eocene this is the distance monkeys would have to raft to get to South America. This hypothesis is invalidated by today's blogpost.

Figure 2. At the start of the Eocene this is the distance monkeys would have to raft to get to South America. This hypothesis is invalidated by today’s blogpost.

Worth remembering…
(since there IS this myth out there) there was no need for a monkey or two from Africa to raft over to South America (Fig. 2). The large reptile tree (LRT, 1753+ taxa) documents descent from Smilodectes (Fig. 1) an adapid living in Texas (Fig. 3).

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

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

Incrementally adding taxa to the LRT
has become less harrowing and more confident because there are no longer any large gaps, no odd enigmas, and lots of similar taxa for new specimens to nest alongside. By getting to this size the LRT has become a tool that no longer needs shaping, but can come out whenever needed to nest new specimens that others find difficult to understand. Even so, the LRT is still subject to constant scrutiny and polishing to further increase its usefullness.


References
Flynn J et al. 1995. An Early Miocene anthropoid skull from the Chilean Andes. Nature 373, 603 – 607.

wiki/Chilecebus

https://pterosaurheresies.wordpress.com/2018/12/10/the-lrt-solves-the-south-american-monkey-puzzle/

https://www.eurekalert.org/pub_releases/2019-08/amon-2ss081919.php

https://nypost.com/2019/08/22/what-a-20-million-year-old-monkey-skull-reveals-about-the-evolution-of-human-brains/

Célik and Phillips 2020 reshuffle basal mammal phylogeny by excluding traits (and taxa)

Célik and Phillips 2020 attempted to
understand the phylogenetic order of basal mammals by excluding traits. They wrote, “Excluding these character complexes brought agreement between anatomical regions and improved the confidence in tree topology.”

Those issues aside, taxon exclusion mars this study. 
The Célik and Phillips cladogram shuffled together unrelated taxa compared to the large reptile tree (LRT, 1737+ taxa). They cladogram (Fig. 1) mixed pre-mammals with placentals and marsupials chiefly due to taxon exclusion.

By employing so many taxa,
the LRT minimizes taxon exclusion and resolves such issues as the Multituberculata / Haramiyida problem. These taxa nest within Glires in the Placentalia in the LRT. Glires is not otherwise well represented in the Célik and Phillips cladogram.

Figure 1. Cladogram from Célik and Phillips 2020 with color overlay showing distribution of taxa in the LRT.

Figure 1. Cladogram from Célik and Phillips 2020 with color overlay showing distribution of taxa in the LRT.

From the abstract
“The evolutionary history of Mesozoic mammaliaformes is well studied. Although the backbone of their phylogeny is well resolved, the placement of ecologically specialized groups has remained uncertain. Functional and developmental covariation has long been identified as an important source of phylogenetic error, yet combining incongruent morphological characters altogether is currently a common practice when reconstructing phylogenetic relationships.”

“Ignoring incongruence may inflate the confidence in reconstructing relationships, particularly for the placement of highly derived and ecologically specialized taxa, such as among australosphenidans (particularly, crown monotremes), haramiyidans, and multituberculates. The alternative placement of these highly derived clades can alter the taxonomic constituency and temporal origin of the mammalian crown group.”

“Based on prior hypotheses and correlated homoplasy analyses, we identified cheek teeth and shoulder girdle character complexes as having a high potential to introduce phylogenetic error.

“We showed that incongruence among mandibulodental, cranial, and postcranial anatomical partitions for the placement of the australosphenidans, haramiyids, and multituberculates could largely be explained by apparently non-phylogenetic covariance from cheek teeth and shoulder girdle characters.”

Figure 1. Subset of the LRT focusing on basal placentals, including multituberculates.

Figure 3. Subset of the LRT focusing on basal placentals, including multituberculates.

Figure 3. Comparing multituberculate origins: Cziki-Sava et al. vs. LRT.

Figure 4. Comparing multituberculate origins: Cziki-Sava et al. vs. LRT.

Based on results recovered in the LRT,
I encourage Célik and Phillips to rerun their analysis with a far larger taxon list. A gradual accumulation of derived traits that mirrors evolutionary events will appear whenever taxon exclusion is minimized.


References
Célik MA and Phillips MJ 2020. Conflict Resolution for Mesozoic Mammals: Reconciling Phylogenetic Incongruence Among Anatomical Regions. Frontiers in Genetics 11: 0651
doi: 10.3389/fgene.2020.00651
https://www.frontiersin.org/articles/10.3389/fgene.2020.00651/full

The spectacled bear (Tremarctos) is not a ‘bear’ in the LRT

Summary of today’s post:
Convergence is rampant in the clade Carnivora, and elsewhere, too, as longtime readers already know only too well. Even so, the LRT (Fig. 3) lumps and splits them all.

Figure 1. Tremarctos ornatus, the spectacled bear of South America, nests with the South American bush dog (Fig. 2) in the LRT (figure 3).

Figure 1. Tremarctos ornatus, the spectacled bear of South America, nests with the South American bush dog (Fig. 2) in the LRT (figure 3).

Most mammal workers consider the spectacled bear,
South America’s only ‘bear’ (genus: Tremarctos ornatus; Fig. 1), a singular bear, genetically and phylogenetically distinct from all other bears. That’s why I added it to the LRT (Fig. 3), where no taxon stands alone.

Figure 2. The South American bush dog, Speothos, nests with the South American spectacled bear, Tremactos, in the LRT.

Figure 2. The South American bush dog, Speothos, nests with the South American spectacled bear, Tremactos, in the LRT.

Surprisingly,
or perhaps not surprisingly, given their geographic proximity, the South American spectacled bear, Tremarctos (Fig. 1), did not nest with the other bears, like Ursus and Arctodus (Fig.3). Instead it nested with the South American bush dog, Speothos (Fig. 2). One is big, the other not so big.

Figure 2. Tremarctos skull in 3 views.

Figure 2. Tremarctos skull in 3 views.

Both the spectacled bear and bush dog are primitive
to the clade of cats + dogs + hyaenas in the LRT (Fig. 3). So, if you’re counting, that makes three origins for carnivores we call ‘bears’. In that regard ‘bears’ are similar to ‘turtles‘ (2 origins),  ‘whales‘ (2 to 3 origins), ‘diapsids‘ (2 origins) and ‘synapsids‘ (2 origins).

Figure 3. Tremarctos nest with Speothos in this subset of the LRT.

Figure 3. Tremarctos nest with Speothos in this subset of the LRT.

Distinct from prior cladograms,
in the large reptile tree (LRT, 1734+ taxa; subset Fig. 3) the South American ‘bear’ (Tremarctos) nests with the South American bush dog (Spetheos). Both nest at the base of the dog + cat + hyaena clade, several nodes apart from extant bears, like Ursus, and the extinct short-face bear, Arctodus, which arises from the wolverine (Gulo).

Figure 2. Speothos, the South American bush dog, skeleton and in vivo.

Figure 2. Speothos, the South American bush dog, skeleton and in vivo.

Speothos veanticus 
(Lund 1842; up to 75cm in length) is the extant South American bush dog, traditionally considered a basal dog. Here Speothos nests at the base of cats + hyaenas + dogs. Miacis is a similar sister basal to sea lions, both derived from another short-legged carnivore, MustelaSpeothos was first identified as a fossil, then as a living taxon. Webbed toes allow this genus to swim more effectively.

Tremarctos ornatus
(Cuvier 1825) is the extant spectacled bear. Not related to other bears, here it nests with another South American member of Carnivora, Speothos, at the base of cats + dogs + hyaenas + aardwolves.

Figure 6. The South American bush dog, Speothos, nests with Tremarctos, at the base of the cat-dog-hyaena clade in the LRT.

Figure 6. The South American bush dog, Speothos, nests with Tremarctos, at the base of the cat-dog-hyaena clade in the LRT.

This may be a novel hypothesis of interrelationships.
If not please provide the prior citation so I can promote it here. Testing taxa that have never been tested together before is what the LRT does.


References
Cuvier F 1825.  In: Geoffroy Saint-Hilaire E.; Cuvier F. (eds.) Histoire naturelle des mammifères, avec des figures originales, coloriées, dessinées d’après des animaux vivans: publié sous l’autorité de l’administration du Muséum d’Histoire naturelle (50). A. Belin, Pari
Lund PW 1842. Fortsatte bernaerkninger over Brasiliens uddöde dirskabning. Lagoa Santa d. 27 de Marts 1840. Kongelige Danske Videnskabernes Selskab Afhandlinger 9:1-16.
wiki/Bush_dog
wiki/Spectacled_bear

Mellivora enters the LRT in a clade of giant honey badgers

Finally we know more about an extinct placental clade
that no one else recognized as an extinct placental clade. Clade members in the LRT included Patriofelis, Sarkastodon and Kerberos (Fig. 1). Now a living member, the honey badger, Mellivora capensis (also Fig. 1), enters the LRT within this clade.

Marsupials or placentals?
The problem is: these three extinct hyper-carnivores have been traditionally considered creodonts and within that clade: hyaenodonts and oxyaenids.
In the large reptile tree (LRT, 1730+ taxa) creodonts are marsupials. Distinct from them, but convergent in many ways, Mellivora, Patriofelis, Sarkastodon and Kerberos nest as clade members within the placental clade, Carnivora. This newly recognized honey badger clade nests between hyper-carnirorous wolverines + short face bears and the stylinodontid + earless seal clade

The placental honey badger clade
dentally converges with the marsupial creodont clade. Don’t put your trust in teeth, as we learned earlier.

According to BioWeb.uwlax.edu
honey badgers are members of the weasel clade, Mustelidae, apart from other mustelids. In the LRT, all derived members of Carnivora, including cats, dogs, bears, seals and sea lions are all derived from the mink/weasel (genus Mustela).

Figure 1. The honey badger clade, Kerboros, Patriolfelis and Sarkastodon. The only living representative is Mellivora to scale.

Figure 1. The honey badger clade, Kerberos, Patriolfelis and Sarkastodon. The only living representative is Mellivora to scale.

Mellivora capensis (originally Viverra capensis Scherber 1777; Fig. 2) is the extant honey badger or ratel, traditionally considered close to weasels. This carnivore has few natural predators because of its thick skin and ferocious defensive abilities.

Figure 1. The honey badger (Mellivora capensis) skull.

Figure 2. The honey badger (Mellivora capensis) skull.

Imagine the unreasonable viciousness of a honey badger
expanded to the size of Sarkastodon (Fig. 1).

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

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

This 3:20 minute honey badger video on YouTube
went viral (95.5 million views) awhile back. Quite the character, now finally understood phylogenetically.

The LRT solves problems
others don’t even think about. Adding taxa is the solution to many phylogenetic problems.


References
Schreber, JCDv 1777. “Das Stinkbinksen”. Die Säugethiere in Abbildungen nach der Natur mit Beschreibungen. Erlangen: Wolfgang Walther. pp. 450–451.

wiki/Honey_badger
wiki/Oxyaenidae