Part 1: A long-legged rodent, the Patagonian mara,
(Dolichotis patagonum, Figs 1–3, Desmarest 1820, 70cm in length), enters the large reptile tree (LRT, 2268 taxa, subset Fig 4) today.
No surprises here,
the mara nests between large capybaras and small guinea pigs in the LRT (subset Fig 4). Basal members of this subclade include extant porcupines (Coendou) and Jurassic Maiopatagium.
Resembling a jackrabbit,
Dolichotis has a long antebrachium, long ears, a bunny tail and only three pedal digits. These diurnal herbivores run like deer. Young are raised in dens.
Part 2: Taxa with a more primitive zygomatic arch
and more teeth than Dolichotus (Fig 3) include multituberculates, plesiadapiformes and carpolestids. Today these taxa move down the tree to Tupaia in the latest revision of the LRT (subset Fig 4). This basal member of the ‘gnawing clade’ is so primitive it still eat insects.
So does
Daubentonia. As of today the Madagascar aye-aye (Figs 5, 6) now nests with Tupaia (Figs 5–7), an Indonesian tree shrew in the LRT (subset Fig 4). So these two genera radiated prior to the splitting up of Gondwana. Both taxa retain a postorbital ring (shared with basal primiates and bats) created by an elongate postfrontal and a rising jugal, among a long list of other shared traits. In Daubentonia the large incisors followed by a toothless diastema are convergent traits found in more derived rabbits, rodents and multituberculates (Fig 7) as well as unrelated artiodactyls, desmostylians and armadillos.
Both of these LRT phylogenetic shifts are welcome news
as they move Jurassic taxa, like multituberculates, closer to the origin of the clade Placentalia and thus keep all the more primitive zygomatic arch taxa together.
Daubentonia madagascariensis
(Gmelin 1788, originally Sciurus madagascariensis; Geoffrey Saint-Hilaire 1795; 40 cm snout-to-vent length) is the extant aye-aye. Originally it was considered an odd squirrel, then an odd lemur. In the LRT Daubentonia returns to Glires, from now on nesting with Tupaia (Figs 4–7). The nocturnal arboreal aye-aye has a long slender digits, particularly manual digit 3, used to probe for insects below tree bark. Note the primate-like grasping medial pedal digit (Fig 5), convergent with primates.
Needless to say,
I should have noticed these interrelationships earlier. Call it either freshman naiveté – or building a house starting with light bulbs and faucets.
If I were to teach evolution to students,
I would do it in evolutionary order, starting with Cambrian worms, not by the random addition of taxa that has slowly grown the LRT to 2268 taxa. That’s why occasional reviews of past data are so important. You won’t see certain mistakes until they pop up by adding the next random taxon, like Dolichotis (Fig 1). As everyone knows, in evolution changes can be subtle. And convergence is rampant. Perhaps these are the reasons why workers don’t want to build their own LRT.
Evolution is a tapestry of gradually changing taxa
that create trait patterns recovered by PAUP. Your own LRT will reflect and model those deep-time generational events. Let us all know if your cladogram differs from this one (Fig 4), because right now it needs confirmation or refutation. It just experienced much needed modification. With that said…
This appears to be a novel hypothesis of interrelationships.
If not, please provide a citation so I can promote it here.
References
Blainville HMD 1838. Recherches sur l’anciennete des Mammiferes insectivores a la
surface de la terre; précéddées de l’histoirc de la science a ce sujet, des principes de leur classification et de leur distribution géographique actuelle. Comptes Rendus Hebdomadaires de Séances de I’Académie des Sciences, 6:738–744.
Desmarest AG 1820. Mammalogie ou description des espèces des Mammifères.
Gmelin JF 1788. Caroli a Linné systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima tertia, aucta, reformata. – pp. [1-12], 1-500. Lipsiae. (Beer).
Geoffroy Saint-Hilaire E 1795. La décade philosophique, litteraire, et politique. Memoires d’Histoire Naturelle 4(28):193– 206.
Owen R 1863. Monograph on the Aye-Aye (Chiromys madagascariensis, Cuvier)
Picone B and Sineo L 2012. The phylogenetic position of Daubentonia madagascariensis (Gmelin, 1788; primates, Strepsirhini) as revealed by chromosomal analysis. Caryologia: International Journal of Cytology, Cytosystematics and Cytogenetics 65(3):223-228.
Raffles TS 1821. Descriptive Catalogue of a Zoological Collection made on account of the Honourable East India Company, in the Island of Sumatra and its Vicinity, under the Direction of Sir Thomas Stamford Raffles, Lieutenant-Governor of Fort Marlborough; with additional Notices illustrative of the Natural History of those Countries. The Transactions of the Linnean Society of London (Linnean Society of London) XIII: 239–340.
Sterling E. 1994. Taxonomy and distribution of Daubentonia: a historical perspective.Folia Primatologica 62:8-13.
The Pterosaur Heresies 