Restoring Plagiomene (incomplete basal placental)

Wikipedia reports,
Plagiomene multicuspis (Fig. 1; Matthew 1918; MacPhee et al. 1989; YPM VP 030624; Wyoming; Paleocene) is an extinct genus of early flying lemur like mammal from North America that lived during the Paleogene.”

Here
using imagination (Fig. 1) to restore the missing parts, scrappy Plagiomene data turns into a more complete skull. Plagiomene had four small molars and a narrow snout between wide robust cheekbones. Those facts and phylogenetic bracketing suggest forward-pointed eyes sitting atop wide cheekbones for bifocal vision.

Figure 1. What little is known of Plagiomene seems to agree with the North American adapid, Smilodectes, among tested taxa.

Figure 1. What little is known of Plagiomene seems to agree with the North American adapid, Smilodectes, among tested taxa. Plagiomene was not added to the LRT.

Here an attempt at restoring the rest of the skull
(Fig. 1) results in a short-snouted taxon with robust cheekbones, more or less similar to Smilodectes (Fig. 1), which has not four, but only three molars and lived during the middle Eocene. An extremely tall coronoid process requires a similarly tall skull. If valid, Plagiomene would be a basal primate, or basal to Primates + Volantia (where dermopterans are a basal taxa).

Possible outgroups,
such as basal Carnivora and Cheiroptera, do not have a similar mandible or molars.

The basal dermopterans,
Palaechthon
(Fig. 1) and Cynocephalus, both have 4 molars, but do not have a tall coronoid process on the mandible.

Earlier we looked at the evidence for
the clade that includes Smilodectes (Adapidae) nesting at the base of the clade of New World monkeys (Platyrrhini). Plagiomene is also from North America.

The last upper premolar
of Plagiomene extends further toward the midline than the molars do. That is unusual in basal mammals. When I find this trait in another basal mammal palate, I will let you know.


References
MacPhee RDE, Cartmill M and Rose KD 1989. Craniodental morphology and relationships of the supposed Eocene dermopterans Plagiomene (Mammalia). Journal of Vertebrate Paleontology 9(3):329–349.
Matthew WD 1918. A revision of the Lower Eocene Wasatch and Wind River faunas. Part V. Insectivora (Continued), Glires, Edentata. Bulletin of the American Museum of Natural History 38(16):429-483.

wiki/Plagiomene
wiki/Smilodectes

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Therocephalians evolved to smaller size? Large Carnivora did not?

Brocklehurst 2019 reports,
“If these results are reliable, they support the traditional paradigm that therocephalians originated as large predators, and only later evolved small body sizes. The patterns observed in mammals do not appear to apply to therocephalians. Mammalian carnivores, once they have reached large size and a specialized bauplan, are apparently unable to leave this adaptive peak. Therocephalians, on the other hand, retreated from the hypercarnivore niche and evolved small sizes later in the Permian.”

Figure 1. Cladogram from Brocklehurt 2019, colors added. Lycosuchus, listed as a basal therocephalian by Brocklehurst, also nests close to cynodonts in the TST. No gorgonopsids are shown here. Biarmosuchus is the outgroup taxon here, a more distant outgroup taxon in the TST.

Figure 1. Cladogram from Brocklehurt 2019, colors added. Lycosuchus, listed as a basal therocephalian by Brocklehurst, also nests close to cynodonts in the TST. No gorgonopsids are shown here. Biarmosuchus is the outgroup taxon here, a more distant outgroup taxon in the TST.

Brocklehurst’s cladogram
posits that Therocephalia and Cynodontia arose as sisters from a last common ancestor: Biarmosuchus. In the therapsid skull tree (TST, 67 taxa, Fig. 4), Therocephalia (including Cynodontia) arises from Gorgonopsia (Fig. 2).

Figure 2. Gorgonopsids, therocephalians and cynodonts to scale.

Figure 2. Gorgonopsids, therocephalians and cynodonts to scale.

The question arises,
what is a ‘large size’ member of the Carnivora? Certainly big cats and walruses (Fig. 3) fall into this definition and do not give rise to smaller ancestors, as Brocklehurst notes. However, if the basalmost member of the Carnivora, Vulpavus, is considered ‘large’ then it breaks the ‘rule’ because it has smaller descendants in the LRT: Mustela and Procyon (Fig. 3). Talpa, the mole, is the smallest member of the Carnivora in the LRT. Talpa has been traditionally omitted from Carnivora studies while being wrongly lumped with the unrelated shrew, Scutisorex, instead.

Figure 3. Carnivora to scale. Note: one branch does increase in size over time (ignoring toy poodles for the moment), while another branch, the one leading to Talpa the mole, shrinks in size.

Figure 3. Carnivora to scale. Note: one branch does increase in size over time (ignoring toy poodles for the moment), while another branch, the one leading to Talpa the mole, shrinks in size. Brocklehurst is correct: once carnivores achieved large size, few to no examples of phylogenetic miniaturization appear in the fossil record.

I wish Brocklehurst 2019 had added
a few sample reconstructions to scale to help readers visualize the size ranges that he found in his cladogram. After all, the subject was ‘size’. I was unfamiliar with the vast majority of therocephalian taxa in his cladogram (Fig. 1).

Figure 4. TST revised with new data on Patranomodon and sister taxa.

Figure 4. TST revised with new data on Patranomodon and sister taxa. Here the therocephalian, Bauria, nests closer to cynodonts than in Brocklehurst 2019 (Fig. 1).

Brocklehurst is correct:
once carnivores achieved large size (Fig. 3), no examples of phylogenetic miniaturization subsequently appear. Brocklehurst contrasted this with therocephalians, presuming that Lycosuchus (Fig. 2) was a basal therocephalian, rather than a basal cynodont by definition.

Remember:
Hopson and Kitching 2001 defined  Cynodontia as the most inclusive group containing Mammalia, but excluding Bauria. In the TST (Fig. 4) Abdalodon and Lycosuchus nest on the cynodont side of Bauria.

In the TST
(Fig. 4), cynodonts show no strong size trends until mammals, like Megazostrodon (Fig. 2), evolved tiny sizes. Therocephalians likewise show no strong size trends either (but then, I have not measured every taxon in the Brocklehurt cladogram, Fig. 1). Those that also appear in the TST are in white boxes, and they appear in several clades within Therocephalia.


References
Brocklehurst N 2019. Morphological evolution in therocephalians breaks the hyper carnivore ratchet. Proceedings of the Royal Society B 286: 20190590. http://dx.doi.org/10.1098/rspb.2019.0590

Numbat genesis in the Early Jurassic

Coelocanth. Tuatara. Numbat.
Name three taxa that have not changed much in hundreds of millions of years.

Figure 1. Myrmecobius, the living numbat, has remained essentially unchanged for nearly 200 million years.

Figure 1. Myrmecobius, the living numbat, has remained essentially unchanged for nearly 200 million years based on the LRT. Note the loss of posterior molars and the simplification of the remaining anterior molars. Orange arrow point to palatal pits that receive the long lower canines.

Extant numbats
(genus: Myrmecobius, Fig. 1) nest in the large reptile tree (LRT, 1412 taxa; subset Fig. 2) basal to Early Cretaceous Anebodon, Middle Jurassic Docofossor and the extant marsupial mole (genus: Notoryctes). All arise from the extant Dasycercus (Fig. 3). So that provides an interesting cladogram with members that span from the Triassic to the present. That means some extant taxa had nearly identical ancestors that shared the planet with the first dinosaurs and pterosaurs.

Figure 2. Subset of the large reptile tree focusing on the basal phytometatheria, including extant numbats, basal to Middle Jurassic Docofossor.

Figure 2. Subset of the large reptile tree focusing on the basal phytometatheria, including extant numbats (Myrmecobius), basal to Middle Jurassic Docofossor.

Myrmecobius fasciatus (Waterhouse 1841) is the extant numbat. Here it nests between Dasycercus and Anebodon. Since an ancestral taxon, Docofossor, is known from the Middle Jurassic, a sister to Myrmecobius had its genesis in the Early Jurassic. The molars are narrow and simplified. This is a marsupial termite eater, convergent with placental termite- and ant-eaters. Over each orbit is the reappearance of an old bone, the postfrontal. The canine is smaller. The jugal is straighter.

Figure 5. Dasycercus, the extant mulgara, is the carnivorous phylogenetic ancestor to the clade that includes numbats, Docofossor and kin in the LRT.

Figure 3. Dasycercus, the extant mulgara, is the carnivorous phylogenetic ancestor to the clade that includes numbats, Docofossor and kin in the LRT.

What’s interesting are the molars in Myrmecobius.
Take a good look (Fig. 1). The molars are narrow and simplified because this taxon eats termites (or vice versa). A phylogenetic descendant, Docofossor (Fig. 5) was considered a docodont based on its simple tooth morphology. Another phylogenetic descendant, Anebodon, was considered a symmetrodont based on its tooth morphology.

The LRT results remind us
not to put so much emphasis on tooth morphology. The LRT makes mammal systematics so much simpler by nesting taxa according to all their tested traits, not just a few, rather plastic, dental traits.

Figure 4. Dasycercus in vivo. This is the extant mulgara, a carnivorous nocturnal basal marsupial.

Figure 4. Dasycercus in vivo. This is the extant mulgara, a carnivorous nocturnal basal phytomarsupial with origins in the Early Jurassic.

Dasycercus cristicauda (originally ‘Chaetocercus‘ Krefft 1867; Peters 1875; 22cm + 13 cm tail) is the extant mulgara, considered a dasyurid marsupial. Here carnivorous, nocturnal Dasycercus nests apart from Dasyurus between Anebodon and Myrmecobius at the base of the herbivorous clade of marsupials. The pouch is reduced to two lateral folds of skin.

Figure 1. Docofossor in situ with DGS tracings.

Figure 5. Docofossor in situ with DGS tracings. This Middle Jurassic taxon nests as a derived descendant of Dasycercus and Myrmecobius in the LRT.

Docofossor brachydactylus (Luo et al. 2015; Middle Jurassic, 160 mya; BMNH 131735; 9cm in precaudal length) was originally considered a member of the Docodontidae along with Docodon and Haldanodon outside of the Mammalia. Here it nests as a Jurassic sister to Anebodon and Notoryctes. Broad, short-fingered hands, larger than the feet, along with other traits mark Docofossor as a digging animal, similar to moles like Talpa and Chrysochloris.


References
Bi S-D, heng X-T, Meng J, Wang X-L, Robinson N and Davis B 2016. A new symmetrodont mammal (Trechnotheria: Zhangheotheriidae) from the Early Cretaceous of China and trechnotherian character evolution. Nature Scientific Reports 6:26668 DOI: 10.1038/srep26668
Gadow H 1892. On the systematic position of Notoryctes typhlops. Proc. Zool. Soc. London 1892, 361–370.
Luo Z-X, Meng QJ, Ji Q, Liu D, Zhang Y-G, Neande AI 2015.Evolutionary development in basal mammaliaforms as revealed by a docodontan. Science. 347 (6223): 760–764.
Peters WCH 1875. Sitzungsberichte der Gesellschaft Naturforschender Freunde zu Berlin 1875: 73.
Stirling EC 1888. Transactions of the Royal Society, South Australia 1888:21
Stirling EC 1891. Transactions of the Royal Society, South Australia 1891:154
Tate GHH 1951. The banded anteater, Myrmecobius Waterhouse (Marsupialia). American Museum Novitates 1521, 8 pp.
Waterhouse GR 1836. Myrmecobius fasciatus. Proc. Zool. Soc. London 4: 69–131.
Waterhouse GR 1841. Description of a new genus of mammiferous animals from Australia, belonging probably to the order Marsupialia. Trans. Zool. Soc., London2, aricle. 11, p 149.

wiki/Dasycercus
wiki/Myrmecobius

Palorchestes and Diprotodon enter the LRT

Two giant odd-looking metatherians,
Palorchestes (Fig. 1, as large as a horse) and Diprotodon (Fig. 2, as large as a hippo), enter the large reptile tree (LRT, 1406 taxa, subset Fig. 3) midway between kangaroos and wombats. So, that settles that conundrum. They’re not wombats and they’re not kangaroos. 

When I was creating the 1986 book,
Giants of Land, Sea and Air ~ Past and Present, I added the ‘giant kangaroo’ next to the largest living kangaroo, Macropus. Less was known back then. I used an extant kangaroo for a model and scaled it up. Now we all know better.

Figure 1. The odd skull of tapir-mimic Palorchestes in 3 views. Colors added.

Figure 1. The odd skull of tapir-mimic Palorchestes in 3 views. Colors added. Dark blue imagines a flexible tapir-like proboscis.

Wikipedia reports, 
“Sir Richard Owen first found what he thought was the fragmentary jaw of a prehistoric kangaroo. It was not until more postcranial elements were found did anyone realize that Palorchestes was actually a different kind of diprotodontid, and not a kangaroo.”

Along with traditional diprotodontids, 
(wombats, koalas and kangaroos) the LRT adds Middle Miocene interatheres and Pliocene toxodons to the wombat clade. This menagerie of morphologies are all herbivores. The last two are former notoungulates.

Figure 2. Diprotodon museum mount and dorsal views of the manus and pes.

Figure 2. Diprotodon museum mount and dorsal views of the manus and pes.

Diprotodon optatum (Owen 1838; Pleistocene 1.5–0.05 mya; 3m in length) is the largest known marsupial of all time. Traditionaly the eight species assigned to Diprotodon nest with wombats and koalas, but here they nest between kangaroos and wombats. The pedes turn inward such that digit 5 is the anteriormost toe on this graviportal beast.

FIgure 4. Diprotodon skull with colors added. This taxon nests midway between wombats and kangaroos.

FIgure 3. Diprotodon skull with colors added. This giant taxon nests midway between wombats and kangaroos.

Palorchestes azael (Owen 1873; Miocene to Pliocene; 2m in length; Figs. 1, 4) had a tapir-like face, likely sporting a similar long proboscis. The lower jaw had a long symphysis, perhaps indicating a protrusible tongue, like an anteater. Large claws tipped the forelimbs (which I have not seen yet, but for the drawing below). Fossils are rare and incomplete.

Figure 5. Palorchestes by Murray 1986. The post-crania is similar to Diprotodon here, perhaps not this completely known.

Figure 4. Palorchestes by Murray 1986 or 1990. The post-crania is illustrated similar to that of Diprotodon, but perhaps not this completely known.

Figure 1. Subset of the LRT focusing on Metatheria after the addition of Diprotodon and Palorchestes. Some new clades are proposed here.

Figure 5. Subset of the LRT focusing on Metatheria after the addition of Diprotodon and Palorchestes. Some new clades are proposed here.

Propalorchestes novaculacephalus (Murray 1986; Trusler and Sharp 2016; Miocene) is a smaller, earlier and plesiomorphic relative of Palorchestes. So far I’ve only seen skull data.

Figure 4. Propalorchestes, the sister to Palorchestes in all analyses, looks more like its kangaroo kin than the other two do.

Figure 6. Propalorchestes, the sister to Palorchestes and Diprotodon in all analyses, looks more like its kangaroo kin than the other two do.

Trusler and Sharp 2016 report,
“Propalorchestes (Middle Miocene) cranial morpholgy, suggests a significantly earlier origin for the highly derived facial anatomy in the Palorchestidae.” 

Given the Middle Miocene appearance of Interatherium,
(Fig. 6) nesting nearby, that seems reasonable.

Figure 2. Interatherium is the surprising ancestor of kangaroos, with a special affinity to the short-face kangaroo.

Figure 6. Interatherium is the surprising ancestor of kangaroos and toxodons, with a special affinity to the short-face kangaroo, Procoptodon.

A few new clade names are proposed here.
Given that the traditional clade Metatheria is no longer monophyletic, unless it also includes the Eutheria, the following clade names are proposed here for the two major monophyletic metatherian-grade clades, one largely herbivorous, the other larger carnivorous:

  1. Phytometatheria, defined as Asioryctes, Glironia, their last common ancestor and all descendants. These include the Diprotodontia listed above and many more, including the omnivores, Petaurus, the sugar glider and its sister Thylacoleo, the marsupial ‘lion’. Docofossor, from the Middle Jurassic, and Anebodon, from the Early Cretaceous are clade members.
  2. Carnimetatheria, defined as Monodelphis, Thylacosmilus, their last common ancestor and all descendants. These include traditional members of the clade, Creodonta, like Oxyaena and Borhyaena. Vincelestes is an Early Cretaceous member, so the genesis of this clade also extends into the Jurassic.

Eomaia, from the Early Cretaceous, and Agilodocodon, from the Middle Jurassic, are sisters to the last common ancestor of both clades.


References
Mackness BS 2008. Reconstructing Palorchestes (Marsupialia: Palorchestidae) – from Giant Kangaroo to Marsupial ‘Tapir’. Proceedings of the Linnean Society of New South Wales, 130, 21-36.
Murray PF 1986. Propalorchestes novaculacephalus gen et sp. nov., a new palorchestid (Marsupialia: Palorchestidae) from the mid Miocene Camfield Beds, Northern Territory Australia. The Beagle, Records of the Northern Territory Museum of Arts and
Sciences 3(1): 195–211.
Murray PF 1990. Primitive marsupial tapirs (Propalorchestes novaculacephalus Murray and Propalorchestes ponticulus sp. nov.) from the mid Miocene of North Australia. (Marsupialia: Palorchestidae) The Beagle, Records of the Northern Territory Museum of Arts and Sciences 7(2): 39–51.
Owen R 1838. Letter in TL Mitchell, Three expeditions into the interior of Eastern Australia. London.
Owen R 1870. On the fossil mammals of Australia. Part III. Diprotodon australis, Owen. Philosophical Transactions of the Royal Society of London. 1870;160:519–578. doi: 10.1098/rstl.1870.0023.
Owen R 1873. On the fossil mammals of Australia. Part IX. Family Macropodidae: Genera Macropus, Pachysaigon, Leptosaigon, Procoptodon, and Palorchestes. Philosophical Transactions of the Royal Society of London 164, 783-803.
Price GJ 2009. Taxonomy and palaeobiology of the largest-ever marsupial, DiprotodonOwen, 1838 (Diprotodontidae, Marsupialia). Zoological Journal of the Linnean Society, 2008, 153, 369–397.
Trusler P and Sharp AC 2016. Description of new cranial material of Propalorchestes (Marsupialia: Palorchestidae) from the Middle Miocene Camfield Beds, Northern Territory, Australia. Memoirs of Museum Victoria 74:291–324.

wiki/Diprotodon
wiki/Palorchestes
wiki/Propalorchestes

https://www.nationalgeographic.com/science/phenomena/2010/10/06/its-a-kangaroo-its-a-llama-no-its-palorchestes/

https://www.wired.com/2010/10/its-a-kangaroo-its-a-llama-no-its-palorchestes/

Deinogalerix: not a giant extinct hedgehog, but close!

Rather,
Deinogalerix (Fig. 1, 2) is a giant moonrat, (Fig. 3) according to its nesting in the large reptile tree (LRT, 1399 taxa)

Figure 1. Skull of Deinogalerix with bones colored in DGS overlay.

Figure 1. Skull of Deinogalerix with bones colored in DGS overlay. Note the separation of the prefrontal and lacrimal along with the large size of the premolars relative to the small molars.

Deinogalerix koenigswaldi  (Freudenthal 1972; Villiera et al. 2013; Late Miocene 10-5mya; skull length 20cm, snout-vent length 60cm) is the extinct giant moon rat (not hedgehog), restricted to a Mediterranean island, now part of a peninsula. Giant premolars and tiny molars make the dentition unusual. Seven species have been identified.

Figure 2. Deinogalerix skeleton.

Figure 2. Deinogalerix skeleton. Snout to vent length = 60cm.

Echinosorex gymnura (Blainville 1838; length to vent up to 40cm, tail up to 30cm, Fig. 3) is the extant moonrat, or gymnure, an omnivore that looks like an opossum or rat. Here it nests with Pholidocercus, a Messel pit armadillo-mimic we looked at earlier here. Distinct from most Glires, the canines are large.

Figure 3. Echinosorex, the extant moonrat, looks like an opossum, but nests with Deinogalerix in the large reptile tree.

Figure 3. Echinosorex, the extant moonrat, looks like an opossum, but nests with Deinogalerix in the large reptile tree.

References
Freudenthal M 1972. Deinogalerix koenigswaldi nov. gen., nov. spec., a giant insectivore from the Neogene of Italy. Scripta Geologica. 14: 1–19.
Villiera B, Van Den Hoek Ostendeb L, De Vosb J and Paviaa M 2013. New discoveries on the giant hedgehog Deinogalerix from the Miocene of Gargano (Apulia, Italy). Geobios. 46 (1–2): 63–75.

.

 

Taxon exclusion mars Mesozoic mammal study

King and Beck 2019
bring us a new phylogenetic analysis restricted to Mesozoic mammals. This represents a massive case of taxon exclusion of basal mammals as demonstrated earlier here, because so many basal mammals are still alive! Think of all the tree shrews, arboreal didelphids, and nearly every little creeping taxon in Glires that nest basal to known Mesozoic mammals. You cannot restrict the taxon list to just those extremely rare Mesozoic mammals.

On the plus side,
King and Beck confirm earlier tree topologies recovered by the large reptile tree (LRT, 1394 taxa) that nest haramiyidans apart from euharamiyidans when they reported, “Tip-dating applied to Mesozoic mammals firmly rejects a monophyletic Allotheria, and strongly supports diphyly of haramiyidans, with the late Triassic Haramiyavia and Thomasia forming a clade with tritylodontids, which is distant from the middle Jurassic euharamiyidans.”

Taxon exclusion
made the authors nest Vintana with euharamiyidans rather than the wombats recovered by the LRT. Other than Vintana, no wombats were included in the King and Beck study—because they are alive. Furthermore, no rodents and aye-ayes were included—because they are alive. So, sans living taxa, King and Beck’s cladogram had no idea where to nest euharamiyidans in the mammal family tree. The wide gamut taxon list of the LRT solves most problems that arise from restricted studies like the King and Beck study.

Figure 4. Mesozoic euthrerians (placentals, in black). Later taxa in light gray. All taxa more primitive than Mesozoic taxa were likely also present in the Jurassic and Cretaceous. None appear after Onychodectes. Madagascar separated from Africa 165-135 mya, deep into the Cretaceous with a population of tenrecs attached. No rafting was necessary. 

Figure 1. Mesozoic euthrerians (placentals, in black). Later taxa in light gray. All taxa more primitive than Mesozoic taxa were likely also present in the Jurassic and Cretaceous. None appear after Onychodectes. Look at all the taxa King and Beck could have added to their analysis!  …and we’re not even looking at the Metatheria and Prototheria here.

More on Mesozoic mammals
here.

References
King B and Beck R 2019. Bayesian Tip-dated Phylogenetics: Topological Effects,
2 Stratigraphic Fit and the Early Evolution of Mammals. PeerJ
doi: http://dx.doi.org/10.1101/533885.

The Miacis-Mustela split within Carnivora

Nesting as the proximal outgroup to all placentals in the LRT
is the slinky, omnivorous, often inverted marsupial didelphid, Caluromys. So that’s the morphology we start with. In the large reptile tree (LRT, 1376 taxa; subset in Fig. 2) Carnivora is the first placental clade to split off. Earlier we looked at the similarity in skulls between Caluromys and didelphid-like basalmost Carnivora, Volitantia, Primates, Glires and Maelestes (at the base of the tenrec-odontocete clade).

Always seeking ‘a gradual accumulation of derived traits’,
basal Carnivora, like civets (e.g. Nandinia) in the LRT are likewise slinky, omnivorous and often inverted. That starts to fade away with the raccoons, Procyon and Ailurus and later evolves to hypercarnivory in the extant mongoose (Herpestes). Based on the appearance of the mongoose sister, Cryptoprocta in Madagascar (135 mya) along with the Paleocene appearance of derived Carnivora, like Miacis and Palaeosinopa, basal Carnivora had their genesis early in the Mesozoic.

Gray 1821 defined Vivveridae
as consisting of the genera ViverraGenettaHerpestes, and Suricata. All tested taxa are basal members of the Carnivora in the LRT (subset in Fig. 2), so this clade is paraphyletic. Bowdich 1821 defined the clade Carnivora as it is used today.

Most derived Carnivora forsake their veggies
as they become highly specialized for predation. Two clades diverge from a common mongoose-like ancestor: one from a sister to Late Paleocene Miacis (Fig. 1), the other from a sister to Mustela, the European mink. Both are small, long-torsoed and short-legged still resembling the placental outgroup taxon, Caluromys.

Figure 1. Mustela and Miacis (the mink/weasel) compared to scale.

Figure 1. Mustela and Miacis (the mink/weasel) compared to scale.

In the LRT
Miacis is basal to the clade of sea lions, dogs, cats, hyaenas and kin (Fig. 2).

Miacis parvivorus (Cope 1872; Heinrich et al. 2008; 30cm in length; Late Paleocene-Late Eocene) was originally considered a pre-carnivore, but here nests as a derived member of the Carnivora, arising from a Mesozoic sister to Herpestes, the mongoose. It was a sister to Mustela and Hyopsodus in the LRT. Miacis had a full arcade of 11 teeth (x4), but the canines and carnassial were smaller. Miacis had retractable claws, like a cat, and was likely arboreal.

In the LRT
extant Mustela is basal to the clade of wolverines, bears, seals and kin (Fig. 2).

Mustela lutreola (Linneaus 1761; extant European mink; up to 43cm in length) is a fast and agile animal related to weasels and polecats. Mustela lives in a burrow. It swims and dives skilfully. It is able to run along stream beds and stay underwater for one to two minutes. Mustela is basal to PuijilaUrsus and other bears, Phoca and other seals.

Importantly 
note the relatively close affinity of dogs (Canis) and cats (Panthera), in the LRT. That becomes a factor in a genomic study below.

Figure 3. Subset of the LRT focusing on Carnivora, the basalmost eutherian clade. Talpa is the European mole. Shrews and shrew-moles nest within the clade Glires.

Figure 2. Subset of the LRT focusing on Carnivora, the basalmost eutherian clade. The two derived clades arising from Mustela and Miacis are shown here.

 

 

How does the clade Carnivora look to traditional paleontologists?
Flynn et al.2005 (Fig. 3) attempted to “assess the impact of increased sampling on resolving enigmatic relationships within the placental clade, Carnivora, by using genomic testing” (so no fossils there). In Flynn et al. the extant Carnivora have their first dichotomy splitting cats from dogs (which are also closely related in the LRT, Fig. 2). No outgroup appears in the Flynn et al. cladogram, which mixes primitive and derived taxa, relative to the LRT. Note, seals + sea lions are monophyletic when fossils are not included. Minks are highly derived here, the opposite of the topology in the LRT. So some relationships are simply inverted, which sometimes happens when the outgroup is not correctly defined.

Figure 4. Carnivora according to Flynn et al. 2005 based on genomic testing.

Figure 3. Carnivora according to Flynn et al. 2005 based on genomic testing. Cryptoprocota is a ‘Malagasy carnivore.”

Once again,
genomic testing does not replicate phenomic testing in deep time. That’s why the LRT is here. So you can test traits vs. genes, always seeking ‘a gradual accumulation of traits’ that echoes or models evolutionary events, without relying on the hope and faith that must come from any analysis that omits fossil taxa. The LRT also provides a list of outgroup taxa back to Devonian tetrapods.

Based on a trait list,
or a photo (Fig. 1), it is easy to see that Miacis and Mustela are closely related. However, in phylogenetic analysis each of these sisters nest at the base of a different derived clade of Carnivora. Cats and dogs remain closely related in the LRT, but both are highly derived relative to the outgroup and basal taxa. The LRT reveals cats are convergent with basal Carnivora, like the cat-like civets.

References
Bowdich TE 1821. An analysis of the natural classifications of Mammalia, for the use of students and travelers. 115 pp.
Cope ED 1872. Third account of new vertebrata from the Bridger Eocene of Wyoming Territory. Proceedings of the American Philosophical Society 12(86): 469-472.
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