How common is gigantism in insular fossil shrews? Examining the ‘Island Rule’ in soricids (Mammalia: Soricomorpha) from Mediterranean Islands using new body mass estimation models

Abstract

The evolution of organismal body size in extant and extinct ecosystems of islands (Island Rule) is receiving much attention at present. Allometric models are a reliable way to predict the weight of extinct species, but are scarce or even absent for some groups of micromammals. To fill the gap, we carried out regression models with extant species of soricids (N = 63) using measurements of teeth, cranium, and postcranial bones, and applied these to fossil insular species and their mainland ancestors. Almost all models are significant (P < 0.05), except for those based on the width of occipital condyles. The femur can be considered the most reliable body-mass predictor, producing estimations not far from those derived from teeth (excepting molar widths). Predictions of insular species (in grams) show that those belonging to the tribe Nectogalini [

Occipital condyle width (OCW) is a highly accurate predictor of body mass in therian mammals

“…Martin [116] used OCW to estimate body mass in extinct mammals; however, these regressions were based on a relatively small (N = 26), taxonomically restricted sample. After Martin [116], only a few studies have used dimensions of the occipital condyles to estimate body mass in extinct terrestrial mammals [65,[117][118][119][120][121]. OCW has been used more frequently to predict body mass in marine mammals (cetaceans, [122][123][124]; sirenians, [69,125]; pinnipeds, [126,127]).…”

Non-native Mammals Are the Main Seed Dispersers of the Ancient Mediterranean Palm Chamaerops humilis L. in the Balearic Islands: Rescuers of a Lost Seed Dispersal Service?

“…On Mallorca island (Balearic archipelago), the native vertebrate fauna of the Upper Pleistocene and the Holocene was composed only of three endemic species: the cave goat Myotragus balearicus (Artiodactyla: Bovidae;25.19-33.34 kg, Palombo et al, 2008), the giant dormouse Hypnomys morpheus (Rodentia: Gliridae; 0.23 kg, Moncunill-Solé et al, 2014) and the Balearic shrew Nesiotites hidalgo (Soricomorpha: Soricidae; 0.023-0.031 kg, Moncunill-Solé et al, 2016). The cave goat was thus the only medium-sized herbivorous mammal present on the islands (specifically, on Mallorca, Menorca and Cabrera).…”

The paradox of anthropogenic enrichment: homogenization and downsizing of insular mammals

“…Chronospecies were considered as single, continuing species and not events of extinction and new arrival. Body mass data (Supplementary Table S2) were compiled from paleontological and contemporary data and regionspecific review works (e.g., Sará and Morand 2002, Jungers et al 2008, MacPhee 2009, Turvey and Fritz 2011, Lomolino et al 2013, Verde Arregoitia et al 2013, Moncunill-Solé et al 2016, van den Hoek Ostende et al 2017, Faurby et al 2018, Rozzi 2018, Athanassiou et al 2019, Morgan et al 2019, Ochoa et al 2021, Besiou et al 2022) and the following online databases: Synopsis of Philippine Mammals at https://archive.fieldmuseum. org/philippine_mammals, Animal Diversity Web at http://animaldiversity.ummz.umich.edu, the Encyclopedia of Life at http://eol.org, GBIF-the Global Biodiversity Information Facility at https:// www.gbif.org/species/2438571.…”