- Note that "camel" as used here refers to all members of Camelidae, and therefore includes llamas, alpacas, guanacos, vicuñas, and various extinct taxa such as Camelops.
The Tylopoda are a group of basal artiodactyls that we know today only by the camels. But in the past they were greatly more diverse. Predating the ruminants, they had just as much diversity as these, but these were all gone before the Pleistocene. But suppose that time took a different turn. In Eocene Split, the climate never cools from the hothouse Eocene levels. These ancient camel relatives in this timeline are among the most successful large herbivorous land mammals on the planet. Rivaled only by the perissodactyls, the camels proper are not among them.
Classification[]
Aside from camelids proper multiple groups of other tylopods are known, most of wich have diversity in Eocene. All of these were effected by the extinction in one form or another. The three major tylopod groups as recognized here are the anoplotherioids, the cameloids, and the oreodonts, plus the xiphodonts, which are of uncertain placement.
Note that multiple groups historically or tentatively placed in Tylopoda are ignored here. Paraphyletic groupings are also for the most part ignored. The dichobunoids are occasionally grouped with the tylopods, but most modern classifications have them being either more basal or as whippomorphs. Based on multiple points of information, importantly stratigraphy and temporal range, the former is here regarded more likely. They'll be given their own page, and are treated as their own group of basal artiodactyls.
Cameloidea[]
†Camelidae[]
The camelids are the most recognizable group of tylopods, to us at least, because on HE they were so successful compared to their relatives. Despite being the only survivors from an ancient dynasty almost as old as the artiodactyls themselves, they thrived in good condition in the cold climates of HE, leaving three genera and six species of extant camelids on HE; a snapshot into Eocene life. But this is completely different in this timeline. At the time of the split they had little diversity, which made them susceptible to extinction. They enjoyed restricted success in North America for the remainder of the Eocene and Oligocene. Going extinct everywhere else by the Oligocene-Miocene boundary, soon even these would go extinct in tropical Miocene climates. Without changing weather patterns that helped jump-start their evolution and decimate their relatives and competition, it seems they weren't capable of surviving. Truly a group designed for the changing ecosystems of the coming Neogene of HE.
Merychoidodontidae[]
Very successful, they diversified greatly, and gave rise to seven major clades, five of which are still extant. The merychoidotontids under Linnaean classificaitons went extinct a few million years ago, but as here phylogenetics are used and the group is alive and kicking, living on four continents: Asia, Australia, and Antarctica, and Europe.
Palaeocamelids[]
Sometime in the drier and cooler times in the Oligocene, one species of oreodont, and only one, made it to South America.
Incertae sedis[]
Depending on the given classification scheme, varying amounts of groups are incertae sedis (of uncertain placement) within Tylopoda, from none, to quite a few. Here however, the xiphodonts are the only group that don't fit under Anoplotherioidea, Cameloidea, or go within merychoidodonts. They might form their own branch, but as they've been varyingly placed across the tree, they are sorted here for conveniance.
†Xiphodontidae[]
On HE, the xiphodonts were a group of relatively unsuccessful tylopods appearing sometime in the Eocene, and probably going extinct sometime in the Oligocene. Note use of the word probably, as they left very little record of their existence to go off of. Only four known genera fit into the group, and only one of these has any post-cranial material, showing a body of a long-legged camel-like creature. Little can be inferred about behaviour because of lack of material, as well as the fact that their closest living relatives, camels, are to distant to make good comparisons. Based on what little is known about body shape a life on the open plain seems plausible, but this is out of place in an Eocene creature. It would appear as if they were a primarily Eocene group adapted to Miocene climate and habitat conditions, doomed to failure by the more successful camels, but this can't be right. Instead it is here inferred that they were small browsers of the forest edge, destroyed by the cooling climate that was about to come. But here, that climate never came. For this is not HE. This is the Eocene Split, a hothouse, forested world.
When the split happened, the xiphodonts were probably at their peak diversity, or just going out of it. But even then, they went into decline, for they would come to last just until the Miocene Thermal Maximum, even if in relative unsuccess. On HE, the camelids became the only Tylopoda to last to the present, their diversity and success only challenged by the merychoidodonts. But as is seen above, this wasn't the case here. That browser niche was left unfilled, and without a drying climate to cause their ultimate demise, the xiphodonts took back their former place. Of course, the mid-Oligocene was a tough time, being when the camelids were at their best (which was still not in good shape), and the Cenozoic was at its driest and coolest. But came did the Miocene, and the few genera like Italidon ("Italy's tooth") and Borealodon ("north tooth") came to be mildly successful as browsers at the forest edge. But this wouldn't stay. Anoplotheres gradually come out from the forests and displaced the niche. The xiphodonts were soon displaced, only present in southern Africa. This made them susceptible to change.
And that change came. The Miocene Thermal Maximum. Unable to adapt, and in lack of diversity, they easily went extinct. On HE, nor here, could they find the road to success. Perhaps in some convoluted world with radically different circumstances they could be among the dominant megafauna. Or perhaps that no matter what, they were doomed from the beginning, unable to see that golden pathway.
| Animalia | |||||
|---|---|---|---|---|---|
| Mammalia | Eutheria | Laurasiatheria | Artiodactyla | Cetancodontamorpha • Dichobunoidea • Ruminantia • Tylopoda | |
| Ferae | Carnivora • Creodonta • Pholidota | ||||
| Meridiungulata | |||||
| Perissodactyla | Chalicotherioidea • Hippomorpha • Rhinocerotoidea • Tapiridae | ||||
| Euarchonta | Dermoptera • Haplorhini • Scandentia • Strepsirrhini | ||||
| Afrotheria • Leptictida • Xenarthra | |||||
| Metatheria | |||||
| Sauropsida | Aves | Neoaves | Passeriformes • Phorusrhacidae | ||
| Choristodera • Crocodylomorpha • Lepidosauria • Testudines | |||||
| Habitats | India • South America | ||||