Skeleton of Early Miocene Bathyergoides neotertiarius Stromer, 1923 (Rodentia, Mammalia) from Namibia: behavioural implication

Abstract

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Fossorial adaptations in African mole-rats (Bathyergidae) and the unique appendicular phenotype of naked mole-rats

“…This is a medium-size rodent with a robust humerus and the ulna exhibiting an enlarged OP 27 , 66 , like other phiomorphs analyzed here. Importantly, B. neotertiarius has a considerably reduced DT (although more developed than in H. glaber ), a less robust femur (with a reduced TT as compared to modern genera), and lack of DFTFi 27 , 66 . The general limb anatomy of this fossil clearly resembles the phenotype of non-fossorial phiomorphs (and H. glaber ) rather than that of other more derived bathyergids, thus suggesting that the limb phenotype of H. glaber is more closely related to the ancestral condition.…”

“…The extinct Bathyergoides neotertiarius (Bathyergoididae) from the early Miocene of East Africa and Namibia 27 , 28 , 66 , one of the proposed ancestors of bathyergids may help us understand the appendicular evolution of early mole-rats. This is a medium-size rodent with a robust humerus and the ulna exhibiting an enlarged OP 27 , 66 , like other phiomorphs analyzed here.…”

“…The extinct Bathyergoides neotertiarius (Bathyergoididae) from the early Miocene of East Africa and Namibia 27 , 28 , 66 , one of the proposed ancestors of bathyergids may help us understand the appendicular evolution of early mole-rats. This is a medium-size rodent with a robust humerus and the ulna exhibiting an enlarged OP 27 , 66 , like other phiomorphs analyzed here. Importantly, B. neotertiarius has a considerably reduced DT (although more developed than in H. glaber ), a less robust femur (with a reduced TT as compared to modern genera), and lack of DFTFi 27 , 66 .…”

“…The general limb anatomy of this fossil clearly resembles the phenotype of non-fossorial phiomorphs (and H. glaber ) rather than that of other more derived bathyergids, thus suggesting that the limb phenotype of H. glaber is more closely related to the ancestral condition. Based on such features, B. neotertiarius has been suggested to exhibit certain degree of burrowing behavior, but to a lower level as compared to extant bathyergids 27 , 66 . It is reasonable to hypothesize that early bathyergids had a comparatively more restricted use of subterranean niches, and that the evolution of the appendicular fossorial phenotype in Bathyergoidea (Bathyergoididae + Bathyergidae) occurred gradually, at least during their early evolution.…”

Functional anatomy and disparity of the postcranial skeleton of African mole-rats (Bathyergidae)

“…Although many aspects of their ecology, physiology, behavior, and evolutionary history have been well-documented (e.g., Bennett and Faulkes, 2000;Šumbera., 2019;Visser et al, 2019;Oosthuizen and Bennett, 2022), a comparative assessment of their postcranial morphology and development including all genera is still lacking. The fossil record of this group is underrepresented, and most fossil taxa are known basically on their cranial and dental material only (Lavocat, 1973;Winkler et al, 2010;Bento Da Costa and Senut, 2022). Several studies of extant bathyergids have focused on the cranial and dental anatomy of a few species (e.g., Berkovitz and Faulkes, 2001;Hart et al, 2007;Barčiová et al, 2009;Van Daele et al, 2009;Gomes Rodrigues et al, 2011;McIntosh and Cox, 2016a;Caspar et al, 2021).…”