New Remains of Camelus grattardi (Mammalia, Camelidae) from the Plio-Pleistocene of Ethiopia and the Phylogeny of the Genus

Abstract

The Old World fossil record of the family Camelidae is patchy, but a new partial cranium and some other remains of Camelus grattardi from the Mille-Logya Project area in the Afar, Ethiopia, greatly increase the fossil record of the genus in Africa. These new data-together with analysis of unpublished and recently published material from other sites, and reappraisal of poorly known taxaallow for a comprehensive phylogenetic analysis showing that C. grattardi is the earliest (2.2-2.9 2 Ma) and most basal species of the genus. We also show that the lineages leading to the extant taxa C. dromedarius and C. bactrianus diverged much higher in the tree, suggesting a recent age for this divergence. A late divergence date between the extant species is consistent with the absence of any fossil forms that could be ancestral, or closely related, to any of the extant forms before the late Pleistocene, but stands in contrast to molecular estimates which place the divergence between the dromedary and the Bactrian camel between 8 and 4 million years ago.

Palaeogenomics reveal a hybrid origin of the world’s largest Camelus species

“…Morphologically, C. knoblochi differs from Bactrian camels in its larger body size and broader infraorbital shelf (Geraads et al, 2019), with most other skeletal characteristics being similar. Geraads et al (2019Geraads et al ( , 2020 suggested that C. knoblochi was more closely related to Arabian camels than to Bactrian camels. In contrast, another study proposed C. knoblochi was similar to, and potentially ancestral to Bactrian camels (Rowan et al, 2018).…”

“…This was followed by the origin of the genus Paracamelus, most likely ancestral to all Camelus, which dispersed from North America into Eurasia and Africa via the Bering Strait around 6.3-5.8 Ma (van der Made et al, 2002). For all Old World camels, Camelus grattardi is thought to be the earliest representative based on remains from the Plio-Pleistocene strata (2.9-2.2 Ma) of Ethiopia (Geraads et al, 2019).…”

“…It is generally thought that C. knoblochi became extinct at the end of Pleistocene and was ultimately replaced by Bactrian camels owing to climatic aridization and plant community transitions (Titov, 2008). Morphologically, C. knoblochi differs from Bactrian camels in its larger body size and broader infraorbital shelf (Geraads et al, 2019), with most other skeletal characteristics being similar. Geraads et al (2019Geraads et al ( , 2020 suggested that C. knoblochi was more closely related to Arabian camels than to Bactrian camels.…”

Plio‐Pleistocene mammals from Mille‐Logya, Ethiopia, and the post‐Hadar faunal change

“…While this family is extremely rare at all African sites, with the single exception of Tighennif in Algeria (Martini and Geraads, 2018), 10 MLP specimens, including a partial cranium, have been recovered from the Seraitu unit. They have been described in detail (Geraads et al ., 2019), and their implications for the phylogeny of Camelus , of which they are among the earliest representatives, have recently been discussed (Geraads et al ., 2020), and they will not be redescribed here.…”

Fossils from Mille-Logya, Afar, Ethiopia, elucidate the link between Pliocene environmental changes and Homo origins

“…from this part of Africa to date and detailed analysis of this skull has been published elsewhere 42 . Hippopotamidae: though remains of this group are common throughout the sequence, there is only one species; it has a hexaprotodont dentition, with a slightly smaller i2 than i1 and i3, thus resembling early forms of the 'aff.…”