Abstract
Madagascar is well known for its diverse fauna and flora, being home to many species not found anywhere else in the world. However, its biodiversity in the recent past included a range of extinct enigmatic fauna, such as elephant birds, giant lemurs and dwarfed hippopotami. The ‘Malagasy aardvark’ (Plesiorycteropus) has remained one of Madagascar’s least well-understood extinct species since its discovery in the 19th century. Initially considered a close relative of the aardvark (Orycteropus) within the order Tubulidentata, more recent morphological analyses challenged this placement on the grounds that the identifiably derived traits supporting this allocation were adaptations to digging rather than shared ancestry. Because the skeletal evidence showed many morphological traits diagnostic of different eutherian mammal orders, they could not be used to resolve its closest relatives. As a result, the genus was tentatively assigned its own taxonomic order ‘Bibymalagasia’, yet how this order relates to other eutherian mammal orders remains unclear despite numerous morphological investigations. This research presents the first known molecular sequence data for Plesiorycteropus, obtained from the bone protein collagen (I), which places the ‘Malagasy aardvark’ as more closely related to tenrecs than aardvarks. More specifically, Plesiorycteropus was recovered within the order Tenrecoidea (golden moles and tenrecs) within Afrotheria, suggesting that the taxonomic order ‘Bibymalagasia’ is obsolete. This research highlights the potential for collagen sequencing in investigating the phylogeny of extinct species as a viable alternative to ancient DNA (aDNA) sequencing, particularly in cases where aDNA cannot be recovered.
Highlights
IntroductionThe island of Madagascar had a wide range of enigmatic Quaternary fauna that are extinct, including ‘giants’ (giant lemurs, giant fossa, elephant birds) and ‘dwarfs’ (dwarf and pygmy hippopotami)
The island of Madagascar had a wide range of enigmatic Quaternary fauna that are extinct, including ‘giants’ and ‘dwarfs’
Prior to in depth LC-MS analyses, the Plesiorycteropus PMF was compared with those of other mammalian groups in order to identify some of the dominant peptides present that differed between the taxa, the highly variable ‘species biomarker’ peptides described previously [27,32]
Summary
The island of Madagascar had a wide range of enigmatic Quaternary fauna that are extinct, including ‘giants’ (giant lemurs, giant fossa, elephant birds) and ‘dwarfs’ (dwarf and pygmy hippopotami). Lamberton [2] recognized that Plesiorycteropus displayed the greatest number of resemblances to aardvarks, but subsequently described a series of features strikingly different from tubulidentates, noting that these other features were more akin to those in pangolins, others to armadillos and anteaters and proposed several hypotheses These included that it is 1) a ‘palaeontological chimera’ composed of characteristics to distantly related mammals; 2) it is representative of a single type of mammal showing convergently evolved characteristics of distantly related mammals with uncertain affinity; or 3) it is a member of a deep mammalian lineage that, isolated by insularisation, retained ancestral traits that have since been lost in derivative lineages facing more intense selection pressures. Throughout most of the early 20th century, it was regarded as an ‘edentate’ (the former grouping that included Tubulidentata with Pholidota, Cingulata and Pilosa) or as a tubulidentate and most closely related to the extant aardvark (Orycteropus; its chosen genus name)
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