Nomenclature proposals for hypothetical relationships within the Mammalia

Updated August 17, 2016 with corrections to some of the nomenclature and graphics .Thanks to M. Mortimer for some valuable suggestions.

Now that several dozen mammal
and stem-mammal taxa have been added to the large reptile tree, and it recovered a distinct topology (Fig. 1), it is not only appropriate but a duty to propose new names for novel clades. Of course, we’ll retain all still-valid clade names.

Introducing new clade names also happened earlier
with the introduction of the clade name, Tritosauria, here online, and in a peer-reviewed academic publication (Peters 2000), when I introduced the Fenestrasauria for Cosesaurus through Pterosauria, long with other clade names for fenestrasaur outgroups, all recovered in phylogenetic analysis.

The new mammal tree topology
(Fig. 1) flips and mixes up the current paradigm (Kriegs et al. 2006) in which (untenably) carnivores are sisters to ungulates and ungulates are sisters to bats and elephants nest between marsupials and primates. None of that makes sense. Where are the gradual accumulations of derived traits? Evidently that was not important to Kriegs et al.  As a remedy we now have this cladogram:

Figure 1. New mammal family tree, a subset of the large reptile tree. Here one can trace a gradual accumulation of derived traits, something the traditional paradigm fails to do. Here the clade names in black refer to small discrete clades in the gray column at right. The red clade names refer to taxa identified by color bars

Figure 1. New mammal family tree, a subset of the large reptile tree. Here one can trace a gradual accumulation of derived traits, something the traditional paradigm fails to do. Here the clade names in black refer to small discrete clades in the gray column at right. The red clade names refer to taxa identified by color bars

Here a gradual accumulation of derived traits can be demonstrated.
All basal taxa are tiny furry arboreal forms that look like each other and later evolve in various ways. Both the major (red) and minor (black) clades are discussed below.

The Red List (Fig. 1)
Each of these major monophyletic clades extend to the ungulates.

A. Kynodontia – Therapsida sans Anomodontia; Hipposaurus, Hippopotamus, their last common ancestor and all  descendants; named for the large canine found in many and most basal clade members

B. Cynodontia – Owen 1861 named Cynodontia, which he assigned to Anomodontia as a family. That is not valid, but the name is retained and in common use. Here, confirming Ruta et al. 2013, the clade is defined as: Procynosuchus, Hippopotamus their last common ancestor and all escendants.

C. Probainognathia – confirming Ruta et al. 2013, the clade includes Probainognatbus and the chiniquodontids and is defined as Probainognathus, Hippopotamus their last common ancestor and all descendants.

D. Trithelodontia – Broom 1912 named this clade, but here it also includes mammals. The clade is defined as Pachygenelus, Hippopotamus their last common ancestor and all descendants.

E. Mammalia – this goes back to Linneaus 1758; provisionally this clade is defined as Sinoconodon, Hippopotamus their last common ancestor and all descendants.

F. Theria – named by Parker and Haswell 1897, include all live-bearing mammals (sans Prototheria); Juramaia has been reported (Luo et al. 2010) as the earliest known therian, but it is not possible to know if it laid eggs or not. Provisionally this clade is defined as Juramaia, Hippopotamus, their last common ancestor and all descendants.

G. Panmetatheria – includes Metatheria (Huxley 1880, taxa more closely related to marsupials than to placentals) + Eutheria. Among tested taxa, Didelphis and the marsupials are also basal therians, traditionally known as metatherians.

H. Eutheria – include all placental mammals (sans Metatheria). The putative marsupial, Monodelphis, lacks a pouch. Eomaia has been reported (Ji et al. 2002) as the earliest known eutherian. Provisionally this clade is redefined as Monodelphis, Hippopotamus, their last common ancestor and all descendants. Basal taxa appear to have been small and arboreal.

I. Pancarnivora – Here the basalmost placental split is between the clade Carnivora and Eomaia. Provisionally this clade is defined as Vincelestes, Hippopotamus, their last common ancestor and all descendants.

J. Panprimates – The next split produced Ptilocercus, Primates, Demoptera, Chiroptera and Pholiodota. Provisionally this clade is defined as Ptilocercus, Hippopotamus, their last common ancestor and all descendants.

K. Panglires – The next split produced rabbit and rodent-like taxa with reduced canines and often enlarged incisors. Provisonally this clade is defined as Asioryctes, Hippopotamus, their last common ancestor and all descendants.

L. Pantenreccetacea – The next split produced long-snouted tenrecs and their sisters the Cetacea (whales). Provisionally this clade is defined as Leptictis, Hippopotamustheir last common ancestor and all descendants.

M. Pancondylarthra – The next split produced the larger basal herbivores, all lacking claws. Provisionally this clade is defined as Onychodectes, Hippopotamustheir last common ancestor and all descendants.

N. Panxenarthra – The next split produced the odd xenarthrans. Provisionally this clade is defined as Orycteropus, Hippopotamustheir last common ancestor and all descendants.

O. Panungulata – (not Paenungulata) The next split produced elephants, sirenians and hyraxes. Provisionally this clade is defined as Stylinodon, Hippopotamustheir last common ancestor and all descendants.

P. Ungulata – This is a traditional clade (Linneaus 1766), but now includes only odd-toed and even-toed ungulates, not aardvarks, hyraxes, sirenians, elephants and/or whales. Provisionally this clade is defined as Tapir, Hippopotamustheir last common ancestor and all descendants.

Q. Phenacodonta – The final split produced Uintatherium and Arsinoitherium on one branch, Hippopotamus and Mesonyx on the other branch. Provisionally this clade is defined as Phenacodus, Hippopotamustheir last common ancestor and all descendants.

The Black List (Fig. 1)
These are the smaller monophyletic clades that branch off sequentially from the main line of descent that ultimately leads to ungulates. Single node taxa are not listed here.

  1. Chiniquodontidae – is represented here by Chiniquodon, Probainognathus and Castorocauda.
  2. Tritheledontidae– includes Pachygenelus, Repenomamus and the Tritylodontidae
  3. Monotremata – includes Sinoconodon and Ornithorhynchus.
  4. Morganucondonta – includes Megazostrodon and tiny Hadrocodium.
  5. Metatheria – includes the marsupials, of course, but not the traditional marsupials, Didelphis or Monodelphis.
  6. Carnivora – includes the larger meat-eating placentals with a carnassial tooth, like Canis and Phoca.
  7. Ptilocercia – includes the smaller omnivorous fanged placentals, like Pteropus and Proconsul, but also the termite-eater, Manis. This is a new clade composed of primates, bats, flying lemurs and pangolins.
  8. Asioryctitheria – named by Novacek et al. 1997, but here includes the smaller omnivorous fangless placentals, like Rattus and Plesiadapis.
  9. Tenreccetacea – includes the long-snouted omnivorous fangless placentals, like Leptictis and now whales, with stem-whale Maiacetus retaining limbs.
  10. Condylarthra – includes large herbivores, like
  11. Xenarthra – a traditional clade includes the anteaters, sloths (Bradypus), armadillos (Dasypus) and now aardvarks (Orycteropus), but not pangolins.
  12. Paenungulata – a traditional clade with Elephas, Dusisiren and Procavia, but no longer Paleoparadoxia and Arsinoitherium, which nest as basal ungulates.
  13. Perissodactylia – a tradional clade of odd-toed ungulates, including Tapirus and Chalicotherium.
  14. Artiodactylia – a traditional clade of even-toed ungulates, including Giraffa and Micromeryx.
  15. Phenacodontidae – Cope 1881 named this clade here expanded to include Uintatherium and Arsinoitherium.
  16. Mesonychidae – Cope 1880 named this clade, but here is redefined by Mesonyx, Hippopotamus, their last common ancestor and all descendants.

Of course this means
that the following traditional and molecule-based clades (Kriegs et al. 2006) have lost their utility due to paraphyly. See if these clades make sense to you. They were not recovered in the LRT.

  1. Atlantogenata – Afrotheria + Xenarthra
  2. Afrotheria – (from Africa): golden moles, elephant shrews, tenrecs, aardvarks, hyraxes, elephants, and extinct forms (not from Africa) sea cows (sirenians)
  3. Boreoeutheria – ungulates, carnivores, primates, rodents, rabbits, tree shrews, flying lemurs
  4. Euarchontoglires – primates, rodents, rabbits, tree shrews, flying lemurs
  5. Laurasiatheria – shrews, pangolins, bats, whales, carnivorans, odd- and even-toed ungulates.
  6. Scrotifera – same as Laurasiatheria sans shrews.
  7. Cetartiodactyla – whales and even-toed ungulates
  8. Ferae – carnivores and pangolins

Earlier studies by McKenna and Bell 1997
listed Xenarthra as the basalmost placental taxon, but they seem a little too derived to show up so early (but then, so are extant monotremes).

Recent restudy 
re-nested Haldanodon (Kühne and Krusat 1972) between Probainognathus and Liaoconodon (Fig. 1). These taxa are basal to Pachygenelus and the Tritylodontia and cannot be considered mammaliaforms, unless Pachygenelus and the Tritylodontia are also considered mammaliaforms. Read more about Haldanodon and the Docodonta here.

I realize that online publication without peer-review
is not going to be accepted, but this hypothesis of interrelationships has to start somewhere. Then again, even with peer-review, after 16 years, Peters 2000 is still not accepted, tested or debated, except for this one totally botched and biased attempt that landed its junior author a PhD.

References
Broom R 1912. On a new type of cynodont from the Stormberg. Annals of the South African Museum. 7: 334–336.
Cope ED 1880. On the genera of the Creodonta. Proceedings of the American Philosophical Society. 19: 76–82.
Ji et al 2002. The earliest known eutherian mammal, Nature 416:816-822.
Kriegs JO, Churakov G, Kiefmann m, Jordan U, Brosius J and Schmitz J 2006. Retroposed Elements as Archives for the Evolutionary History of Placental Mammals. PLoS Biology. 4 (4): e91. doi:10.1371/journal.pbio.0040091. PMC 1395351free to read. PMID 16515367.
Kühne and Krusat 1972. Legalisierung des taxon Haldonodon (Mammalia, Docodonta). Neues Jahrbuch für Geologie, Paläontologie and Mineralogie, Monatshefte 5: 300-302.
Linnaeus C 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.
Linneaus C 1766. Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio duodecima, reformata. Holmiae. (Laurentii Salvii).: 1-532.
Luo Z-X, Yuan C-X, Men Q-J and JiQ 2011.A Jurassic eutherian mammal and divergence of marsupials and placentals. Nature 476: 442–445. doi:10.1038/nature10291.
McKenna MC, Bell SG 1997. Classification of Mammals above the Species Level. New York: Columbia University Press.
Novacek MJ, Rougier GW, Wible JR, McKenna MC, Dashzeveg D and Horovitz I 1997. Epipubic bones in eutherian mammals from the Late Cretaceous of Mongolia. Nature 389:483-486
Owen R 1861. Palaeontology, or a systematic summary of extinct animals and their geological relations. 2nd ed. Adam and Charles Black, Edinburgh, xvi + 463 p.
Peters D 2000. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.

wiki/Mammalia
wiki/Mammaliaformes

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5 thoughts on “Nomenclature proposals for hypothetical relationships within the Mammalia

  1. Ignoring all the other issues with this, there are numerous problems with your proposed nomenclature.
    – Monotremata is the crown group. The total group of 3 is Prototheria/Yintheria.
    – Your Metatheria is paraphyletic, and should be either the Didelphis clade (which makes Australian marsupials eutherians) or the australidelphians (which excludes Didelphis from Theria).
    – Your Carnivora is Pan-Carnivora, while actual Carnivora is the Nandinia+ group.
    – Your Ptilocercia is Archonta.
    – Asioryctitheria is a terrible name for clade 8. Follow the terrible mammalogist naming tradition and call it Insectoglires.
    – You’d really have all cetaceans inside of Tenrecidae? Tenrecetacea, I say.
    – Your Xenarthra is Edentata- what researchers called the group before they realized aardvarks weren’t a member.
    – Surely you’d want the Ancodus+Micromeryx+Giraffa clade to be Artiodactyla, not anything in your hippo group P. You basically found hippos to not be artiodactyls. Try coding a pig and a camel.
    – Ungulata is clade N, not clade 13.
    – Cynodontia is clade A. Everything below Thrinaxodon is Eucynodontia, which has priority over Probainognathia.
    – All of your Para- names would be frowned upon by most authors, since Para- means next to, near, beside, etc.. So parareptiles are next to reptiles. Paraves is the exception which is generally disliked, but established so begrudgingly used.

  2. Mickey,
    I appreciate your knowledge and willingness to help here. Let’s go through your comments together. I’m like a freshman when it comes to so many things, especially mammals. And I was not as precise as I could have been, but opted for simplification.
    1. Prototheria – good catch
    2. Metatheria – indeed paraphyletic at present. Wonder how that will play out with additional taxa.
    3. Pancarnivora – indeed paraphyletic at present. Carnivora identified by the carnassial.
    4. Ptilocercia is not Archonta, which includes all tree shrews (Tupaia is out) and plesiadapiformes (Plesiadapis is out), but it also includes bats (sometimes in, sometimes out) and pangolins.
    5. Asioryctitheria – is a name I did not make up. When you look up Asioryctes, that’s what pops up in Wiki
    6. Tenrecetacea – good name!
    7. Edentata – I see pangolins were also included within Edentata. So, it’s 50/50 on which way to go
    8. Artiodactyla – good catch, I overlooked that.
    9. Hippos not artiodactyls? – good suggestion for the weekend
    10. Ungulata is not clade 13, correct!
    11. Cynodontia, yes, there was a phase shift in graphics that I see now
    12. Para- I’m at a loss to find another just as simple prefix to get across the idea.

    Thanks for your time and efforts!

    • 4- We don’t need to fall into the mammalogist flaw of not using a name because one or two groups are now excluded. That’s how we got Euarchonta- “it doesn’t include bats, so it can’t be Archonta.” Your Archonta excludes Tupaia and includes pangolins, whatever.
      5- Yeah, it’s a name for a few taxa close to Asioryctitherium. Not for an insectivore plus glires clade.
      10- Note aardvarks and condylarths were considered ungulates, so you could easily have this as clade N or M.
      12. Pan- isn’t it either, as that’s a prefix for the total group (closer to the clade than any living taxon). So Dimetrodon and Cynognathus are pan-mammals, because they’re closer to mammals than to any other living taxa. So your Pan-taxa are failures too. There’s no simple prefix for your idea because we don’t name taxa this way (____-ia where ____ is the first branching clade). You’ll have to be more imaginative.

  3. Within genera, and perhaps larger clades, genetic studies perform well. Across larger divides they do not. As always, the yardstick for judging any and all studies comes from the recovery of ‘a demonstrated gradual accumulation of derived traits’ otherwise known as ‘microevolution.’

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