Recommended audio series on the natural history of the pampas

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to be continued...

Publicado el agosto 26, 2023 05:20 TARDE por milewski milewski


Many thanks for this series

Publicado por paradoxornithidae hace 11 meses


Publicado por beartracker hace 11 meses

The following were the genera of medium-size to large mammals (excluding those weighing one tonne or more) in the Lujanian fauna (of the Late Pleistocene) in what is now Buenos Aires province of Argentina.


*Asterisks show families that are wholly extinct


Antifer (deer, and and
Paraceros (deer,
Morenelaphus (deer, ?200 kg,,and%20the%20broadest%20geographic%20distribution.)

Camelidae (
Eulamaops (150 kg, similar in size to extant guanaco)
Lama (genus still extant, and,1984%3B%20Wheeler%2C%201995).)
Palaeolama (forest camelid, 200 kg)

Catagonus (peccary, and


Tapirus (tapir, no larger than modern spp., and

Equidae (
Equus (horse/zebra, 400 kg,,closely%20related%20to%20true%20horses.)
Hippidion (horse-like, and


*Macraucheniidae (
Xenorhinotherium (>800 kg,


Neochoerus (giant capybara, possibly not tied to water, ?100 kg, and


Nothropus (ground sloth)
Nothrotherium (ground sloth)

Ocnopus (ground sloth)

Ocnotherium (ground sloth)

Scelidodon (ground sloth)
Scelidotherium (ground sloth)
Valgipes (ground sloth)


Holmesina (giant armadillo, 200 kg)
Pampatherium (giant armadillo up to 200 kg)

Propraopus (relative of extant armadillos,

Eutatus (glyptodont)
Glyptotherium (glyptodont)
Hoplophorus (glyptodont)
Neuryurus (glyptodont)
Parapanochthus (glyptodont)
Neosclerocalyptus (glyptodont)


Smilodon populator (sabre-tooth cat, >300 kg)

Arctotherium (deep-jawed bear, 250 kg)

Aenocyon (wolf, 65 kg, and and
Dusicyon (dog-like, 30 kg)
Protocyon (dog-like, 30 kg)


Protopithecus (monkey, 23 kg)

Publicado por milewski hace 11 meses

We saw, in part 2 of the pampas series of audio podcasts, that the only familiar family, among the various megaherbivores (body mass > 10 tonne = 1,000 kg) of the Lujanian fauna of Buenos Aires province, was the Camelidae.

All the other megaherbivores here, ranging from elephant-like gomphotheres through giant ground sloths and glyptodonts to notoungulates and a litoptern, belong to now-extinct families.

When it comes to the mammals of 20-999 kg in the same fauna, there are more familiar elements, because the extinctions have not been as profound.

Genera which survive - albeit only elsewhere - in modern times are Lama, Catagonus (, Equus, and Tapirus.

There is even more familiarity at the level of families. The Lujanian mammals of 20-999 kg included deer (Cervidae), camels (Camelidae), peccaries (Tayassuidae), equids (Equidae), tapirs (Tapiridae), cats (Felidae), bears (Ursidae), dogs (Canidae), armadillos (Dasypodidae), cavies (Caviidae), and atelid monkeys (Atelidae).

This leaves seven families, in this body mass-range, that are as unfamiliar as in the case of the megaherbivores. These are mainly xenarthran ('edentate') families, plus the litoptern family Macraucheniidae - the latter belonging to an extinct order.

As in the case of the megaherbivores, the xenarthrans of < 1 tonne have so many sympatric genera that it is hard to imagine how they all coexisted.

I refer to seven genera (in four families) of Pilosa (ground sloths), and nine genera (in three families including two extinct families) of Cingulata. Glyptodonts belong to Chlamyphoridae, and pampatheres belong to Pampatheriidae.

Publicado por milewski hace 11 meses

Canis dirus has now been classified as Aenocyon dirus, with the Aenocyon lineage being closer to Lupulella than Canis, if I'm not mistakened.

Publicado por paradoxornithidae hace 11 meses


Many thanks for correcting my inexcusable error. It is indeed significant that dire wolves were distinct from Canis, much as sabre-tooth cats were distinct from Panthera.

Publicado por milewski hace 11 meses

Apparently Lycalopex gymnocercus (Pampas fox) can hybridise with Canis familiaris (domestic dog) (source:

Publicado por paradoxornithidae hace 11 meses

If this was possible, one can suppose Aenocyon dirus could've hybridised with Canis lupus.

Publicado por paradoxornithidae hace 11 meses


Many thanks for pointing this out.

It seems significant that a species of Lycalopex is the closest thing to a coyote in South America (

The failure of the coyote to invade South America is usually taken for granted. However, it is noteworthy, and partly explained by the view that Lycalopex takes the place of Canis in South America, with a similar niche as well as enough phylogenetic similarity that intergeneric hybridisation remains possible. The real surprise is, perhaps, that the hybridisation was not with Lycalopex culpaeus.

As for hybridisation between Canis and Aenocyon, this does indeed seem possible. The clearest morphological distinction between the two genera seems to be in the baculum ( and and

Because this is the bone in the penis (, this may indicate a mode of reproductive separation notwithstanding the genetic compatibility.

Please bear in mind that canids have a copulatory tie, so the form of the penis may matter.

Putting this differently:

If one were to perform artificial insemination, probably there would be no problem crossing Aenocyon with Canis, producing fertile offspring, and blurring the genera. And possibly such blurring actually happened in nature just before Aenocyon went extinct. However, a barrier to hybridisation possibly exists in the form and function of the genitals, analogous to a 'lock-and-key' mechanism.

Publicado por milewski hace 11 meses

A reminder of the distribution ranges of the various spp. of Lycalopex:

Publicado por milewski hace 11 meses

I hadn't thought of the anatomy of Aenocyon in my previous comment. It's possible what you noted might have been an inhibitor of hybridisation, and certainly, it's an important detail that I missed out on.

Publicado por paradoxornithidae hace 11 meses

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