Ontogenetic allometry reveals the imprint of myrmecophagy in the skull of the numbat, Myrmecobius fasciatus Waterhouse, 1836 (Marsupialia: Myrmecobiidae)

GIANNINI, N.P.; ABDALA, FERNANDO; FLORES, DAVID A.

ALCHERINGA

TAYLOR & FRANCIS LTD

Lugar: Londres; Año: 2023

0311-5518

Ontogeneticallometry, the covariation of shape with size over the course of development,represents a fundamental component of morphological diversification that canvary across species and in association with ecological factors. Ontogeneticallometry patterns for the skull have been described for species from severalmarsupial lineages, associated with common dietary niches, e.g., carnivory. Wehere conduct a novel detailed examination of cranial ontogeny in the numbat (Myrmecobiusfasciatus), unique among marsupials in being myrmecophagous andadopting a strictly diurnal habit. We investigated ontogenetic allometry usingmultivariate analyses in a postnatal series (n=28) of complete numbat skulls toestimate the rate of growth of its major constituent elements, described by 15measurements. We find positive allometry for length of the nasals and palate,which relates directly to the remarkable rostral elongation in the species, inaddition to several other ontogenetic changes. These comprise negativeallometry of palate breadth, elongation of upper and lower toothrows thatproduces diastemata between weakly structured teeth, and decreasing muzzleheight, all of which contribute to the development of a long, tapering, narrowrostrum, with limited mastication ability, as seen in the scarce temporal spaceand poor development of crests and processes. Our specific allometric resultsand comparisons, together with qualitative observations, reveal a distinctimprint of myrmecophagy on skull ontogeny and help explain the development andevolution of specialized feeding function in the numbat.