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| Morphology | Ecology and taphonomy | External Literature Search | Age range and collections |
Mcdonaldocnus
Taxonomy
Mcdonaldocnus was named by Gaudin et al. (2022).
It was assigned to Nothrotheriidae by Gaudin et al. (2022).
It was assigned to Nothrotheriidae by Gaudin et al. (2022).
Synonymy list
| Year | Name and author |
|---|---|
| 2022 | Mcdonaldocnus Gaudin et al. |
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
G. †Mcdonaldocnus Gaudin et al. 2022
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†Mcdonaldocnus bondesioi Scillato-Yané 1979
†Mcdonaldocnus villarroeli Gaudin et al. 2022
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Invalid names: Xyophorus villarroeli St-Andre 1996 [objective synonym]
Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| T. J. Gaudin et al. 2022 | Small bodied member of Nothrotheriidae, similar to or smaller in size than Pronothrotherium. It lacks derived features of more derived nothrotheriids (i.e., Pronothrotherium, Aymaratherium, Mionothropus, Nothrotherium and Nothrotheriops) or retains mega- therioid symplesiomorphies, including lack of a canal from the occipital artery system perforating the paroccipital process; ante- rolaterally directed root of zygoma; lack of an odontoid process on astragalus; lack of broad dorsal exposure of fibular facet; broadastragalar neck; ectal facet not transversely oriented; small sustentacular facet; cuboid facet on the plantar surface of astragalus; presence of a ridge connecting the head to the distal lateral trochlea in distal view; presence of a non-articular area on the plantar edge of the lateral trochlea, lateral to the head in distal view; distal contact between the fibular and ectal facets in lateral view; and minimal lateral exposure of ectal facet in lateral view.
Can be distinguished from both basal megatherioids and other nothrotheriids by the following autapomorphies: elongated man- dibular symphysis, with cf1 anterior to posterior edge of symphysis; short diastema, less than the maximum mesiodistal length of mf1; deep longitudinal grooves on the labial and lingual surfaces of mf1 and mf2; very rugose external surface of ectotympanic; contact between styliform process of ectotympanic and pterygoid; very high stapedial ratio; very small anteroventral process of tegmen tympani; subarcuate fossa strongly reduced; presence of medial prominence of petrosal; wide sulcus tali on ventral surface of astragalus; shallowly concave ectal facet. |
Measurements
No measurements are available
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| Source: o = order, subc = subclass, c = class, subp = subphylum | |||||
| References: Carroll 1988, Hendy et al. 2009, Lillegraven 1979, Ji et al. 2002, Nowak 1999 | |||||
Age range: base of the Langhian to the top of the Huayquerian or 15.98000 to 5.00000 Ma
Collections (9 total)
| Time interval | Ma | Country or state | Original ID and collection number |
|---|---|---|---|
| Burdigalian - Langhian | Bolivia | Xyophorus bondesioi (91435) | |
| Langhian | Argentina (Chubut) | Xyophorus sp. (133676) | |
| Serravallian - Tortonian | Argentina (La Pampa) | M. sp. (231228) | |
| Tortonian | Argentina (Chubut) | Xyophorus sp. (201907) | |
| Tortonian | Bolivia (La Paz) | Xyophorus villarroeli (90023) | |
| Chasicoan | Argentina (Buenos Aires) | M. bondesioi (212344) | |
| Huayquerian | Argentina (La Pampa) | M. sp. (152061 204363) | |
| Messinian - Zanclean | Argentina (La Rioja) | Xyophorus bondesioi (152263) |