Cranial ontogeny ofLutreolina crassicaudata (Didelphidae): a comparison withDidelphis albiventris

Abstract

2003. Cranial ontogeny of Lutreolina crassicaudata (Didelphidae): a comparison with Didelphis albiventris. Acta Theriologica 48: 1-9.Metatherians experience the greatest developmental changes during extrauterine life. Following previous studies on Didelphis albiventris Lund, 1840, we examined the postweaning cranial allometry of size of the Neotropical marsupial Lutreolina crassicaudata (Desmerest, 1804). Our aim was to compare growth patterns of both species to identify traits particular to each species and traits common to both species. This may contribute toward identifying a common developmental plan for didelphids. We measured 15 cranial variables in 32-43 specimens from just-weaned young to old adult. Total length of the skull was the estimator of overall size in least squares and reduced major axis regressions. The skull of Lutreolina crassicaudata grows at a rate slower than the overall change in size in its neurocranial components, palate, and postcanine rows, and it grows relatively faster in the rest of the splanchnocranium. This pattern closely resembles that of Didelphis albiventris, from which it differs mainly in the allometry of the muzzle. In both species, allometry explains most postweaning changes of the trophic apparatus on functional grounds, in relation to interspecific differences in diet. We hypothesize that most local allometric departures from a generalized didelphid plan would relate to main dietary trends.

Comparative Postnatal Ontogeny of the Skull in Dromiciops gliroides (Marsupialia: Microbiotheriidae)

“…Qualitative and allometric analyses of growth allowed us to explore how distinctive the skull development of D. gliroides is in a context of comparative ontogeny. On the basis of our previous work on large-sized didelphids (Abdala et al, 2001;Flores et al, 2003), we show that the overall pattern of skull growth in D. gliroides is highly conservative. In turn, we contend that a minority of the observed developmental trends may be uniquely derived, but this remains to be contrasted with yet unknown ontogenetic patterns of small-sized didelphids and australidelphians.…”

“…C and G). Abdala et al (2001) and Flores et al (2003) observed these changes in two didelphids and proposed that the adjustment of the jaw articulation through the expansion of the condyle facilitates the safety of the mandibular movements during strenuous bites. A functionally related change is the development of the masseteric line in adults, for insertion of the deep masseter muscle (based on Didelphis marsupialis; Turnbull, 1970).…”

Phylogenetic Relationships and Classification of Didelphid Marsupials, an Extant Radiation of New World Metatherian Mammals

“…The nascent literature on didelphid cranial morphometrics is not large, but it includes studies of intraspecific ontogenetic variation (Abdala et al, 2001;Flores et al, 2003), multivariate comparisons of conspecific species (e.g., Ventura et al, 1998Ventura et al, , 2002Cerqueira and Lemos, 2000), analyses of evolutionary rates (Lemos et al, 2001), geometric modeling of taxonomic variation (Astú a de Moraes et al, 2000), and preliminary attempts to explain shape differences in functional terms (e.g., Medellín, 1991).…”

A Revision of the Didelphid Marsupial Genus Marmosa Part 1. The Species in Tate's ‘Mexicana’ and ‘Mitis’ Sections and Other Closely Related Forms

“…Like other didelphid marsupials (Gardner, 1973;Abdala et al, 2001;Flores et al, 2003), young mouse opossums are weaned long before they are morphologically mature, with the result that mixed-age series of conspecific individuals often include specimens that differ conspicuously in size and size-correlated (allometric) proportions. Because immature (juvenile and subadult) individuals seldom exhibit all the diagnostic traits that allow confident taxonomic identifications of adults, careful attention to dental indicators of morphological maturity is important.…”