Describing species' ecological strategies enables us to condense ecological information and to express it in evolutionary terms. However, the process of categorizing species is hampered by methodological difficulties and insufficient development of the typology and nomenclature of different strategies. In this article an approach for overcoming these difficulties is proposed. For a precise description of mammalian substrate utilization, it is better to combine two characteristics rather than use only one. The categorization should reflect: (1) the media or substrates primarily used for foraging; and (2) the media or substrates primarily used for sleeping. The numerous substrate utilization strategies of mammals fall into five broad groups: (1) aquatic and semiaquatic;(2) subterranean; (3) terrestrial and subterranean-terrestrial; (4) arboreal and semiarboreal; and (5) aerial and semiaerial. Three main mammalian feeding strategies are proposed: animalivorous, frugivorous, and herbivorous. An example of ecological classification of mammals in terms of substrate utilization and feeding strategy is provided.

An ecomorphological approach was used to estimate the probability of interspecific competition between introduced and native rodents in Madagascar. Comparison of body size, body construction, and craniodental characters leads to the conclusion that there is a high probability of competition between introduced Rattus rattus and the following native taxa: all species of Nesomys, larger semiarboreal Eliurus species (e.g. E. tanala, E. webbi), and especially Gymnuromys roberti. The competitive relationships between introduced rodents and the remaining species of the Nesomyinae have a low probability or are improbable, except possibly for Mus musculus and the so far poorly studied Monticolomys koopmani and Voalavo species.

The giant rat of Martinique Island, Megalomys desmarestii (Fischer, 1829) became extinct at the end of the 19th or the very beginning of the 20th century. Little is known about its habits. The goal of this research was to reconstruct its ecology using the external and craniodental morphological characters of available museum specimens. On the basis of ecomorphological analysis some suggestions are made about the locomotor abilities, ecological strategies, adaptive evolution, and origin of this rodent. It is proposed that M. desmarestii foraged mostly on the ground and sheltered in burrows. Its main food was seeds and fruits, including nuts. It was crepuscular rather than strictly nocturnal or diurnal. The general trends of its adaptive evolution were: (1) increasing body size, (2) transition from an arboreal to a terrestrial/subterranean way of life, and (3) adaptation to eating hard-covered fruits. Thus, the ancestor of M. desmarestii was probably smaller and had arboreal or semiarboreal habits. The granulated structure of the soles of M. desmarestii's feet supports a close relationship with Nectomys.

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