The biology and palaeontology of the Peramelemorphia: a review of current knowledge and future research directions

Abstract

Bandicoots and bilbies (Marsupialia : Peramelemorphia) represent the dominant omnivorous clade of Australasian marsupials and, as ground-dwelling, small- to medium-sized mammals, have not fared well in the 200 years since European settlement. Unlike large or charismatic marsupial species, the cryptic nature of bandicoots and bilbies tends to keep them out of the public eye, at a time when public interest plays a significant role in conservation efforts. The inconspicuous ‘rat-like’ appearance of many bandicoots and a generalist ecological strategy belie a complex biology of adaptive traits and evolutionary diversity. For a few species these biological traits have enabled them to make use of urban environments. In the main, however, peramelemorphians are facing ongoing pressure from introduced predators and human impacts. Basic biological information for many species, particularly those from New Guinea, is still lacking. In this review, we examine advances in the knowledge of the biology of this group over the past 25 years including anatomical, physiological and ecological studies. We also provide a comprehensive review of the fossil records of bandicoots in order to provide an up-to-date platform for future studies. From this work, it is clear that there is still much to be done regarding the taxonomy and biology of these animals before a more detailed understanding of the evolutionary history of this group can be elucidated.

Bandicoot fossils and DNA elucidate lineage antiquity amongst xeric-adapted Australasian marsupials

“…An alternatively derived squamosal-frontal contact is shared by all crown perameloids, and might be diagnostic for this radiation, but was not a major driver of our topologies (see Supplementary Data). Moreover, the monophyly of Yarala 21 as a separate sister grouping to Perameloidea was equivocal (Supplementary Table S3), leading us to question the taxonomic utility of Yaraloidea based on these primitive states alone32021.…”

“…Peroryctes tedfordi were variously interpolated amongst crown Perameloidea, with Madju positioned as a sibling lineage. This rendered the genus Bulungu polyphyletic (although constraint trees showed no significant difference: Supplementary Table S3), and the respective classifications of Kutjamarcoot and Crash as either a stem perameloid14 or stem peramelids312, were likewise uncertain (Supplementary Figs S11 and S12). Similarly, the earliest dated peroryctine14, cf.…”

“…However, yaralids are united by a single unique symplesiomorphy – retention of a ‘complete’ centrocrista formed by the postparacrista and premetacrista on the upper molars21. This has since been identified in a range of Oligocene−Miocene bandicoots161718, and is ancestral amongst marsupials25, but otherwise lost in crown perameloids (defined by separated postparacristae-premetacristae) prompting assertions of a Miocene ‘bottleneck’ within Peramelemorphia, as well as other Australasian marsupials26, whereby the radiation of crown taxa occurred only after the decline of rainforest-restricted stem forms, perhaps in response to climate change, ecological competition and/or vicariance events3910151920212223242627.…”

“…Most are small to medium sized (up to 5 kg) terrestrial omnivores occupying a spectrum of rainforest to desert habitats23. Molecular studies14 have defined three taxonomic subdivisions within the crown superfamily Perameloidea (Fig.…”

“…This contrasts with published morphological data, which posits both a late Miocene–Pliocene diversification of Australian Peramelinae concurrent with increasing aridity910, and late Miocene vicariant origins for Peroryctinae and Echymiperinae (historically united as Peroryctidae)11 accompanying New Guinean tectonic uplift. Such arguments are inferred from the fossil record, which has yielded no generically referable crown taxa older than the early Pliocene311. Fossil evidence of extant higher-level clades is also extremely sparse, consisting of isolated dental remnants from the middle Miocene putative basal peramelid Crash 12 and thylacomyid Liyamayi 12, as well as cranial-mandibular elements of the early–middle Miocene stem perameloids Madju 13 and Kutjamarcoot 14.…”