First Crania and Assessment of Species Boundaries in Nimbadon (Marsupialia: Diprotodontidae) from the Middle Miocene of Australia

• DOI: 10.1206/666.1
• Publication Date: 2010-03-16T16:06:38Z
• Authors: Karen H. Black; Suzanne J. Hand
• Keywords: Crania; Variation (astronomy); Sexual dimorphism

Abundant, exceptionally well-preserved cranial material of the zygomaturine diprotodontid Nimbadon lavarackorum is described from AL90 site, a middle Miocene deposit in Riversleigh World Heritage Area, Queensland, Australia. The has enabled comprehensive assessment expected level morphological variation within fossil marsupial species single locality, thus forming benchmark for determining boundaries extinct marsupials. Variation assessed by quantitative and qualitative means. Univariate analyses N. dental dimensions indicate low coefficients consistent with values populations. Conversely, high levels variation, particularly structures previously deemed phylogenetically significant, such as upper third premolar. Some may be due to sexual dimorphism or ontogeny but there appears degree intraspecific variation. Features once regarded distinguish whitelawi type fall that herein junior synonym lavarackorum. Comparison Neohelos stirtoni suggests was less variable overall, reflecting differences between taxa body size, home range, habitat preference stability. relatively small (75–120 kg), possibly gregarious browsing probably restricted closed-forest habitats.