For example, the pachycephalosaurs Dracorex, Stygimoloch and Pachycephalosaurus are now known to be ontogenetic stages of the same species, even though their cranial ornamentations are grossly different (Horner & Goodwin, 2009). As noted above, the 17 named species of Triceratops now appear to be reducible to one species with two anagenetic morphs that succeed each other through time; in addition, the genus Torosaurus
now appears to be the adult form of Triceratops (Scannella & Horner, 2010). No living vertebrates do anything like this, and it testifies to the complex social structure of these dinosaurs. If we try to explain their biology using untested or untestable analogies to living PLX4032 in vitro forms, or to accept a proposed function of a structure simply on the basis of what it ‘looks like’ it might do, we should expect to overlook important insights into some of the most marvelous animals ever to have walked the Earth. We are grateful to Knell and Sampson for their stimulating arguments, to Randall B. Irmis and David B. Wake for reviewing the manuscript, and to Katie Brakora, John Scannella and Denver Fowler for helpful discussion, without of course implying their agreement with us. “
“School of Marine
and Tropical Biology, Faculty of Science and Engineering, James Cook University, Cairns, Australia Sociality is environmentally and phylogenetically determined and can vary intraspecifically BAY 80-6946 datasheet and interspecifically. We investigated the reasons for group living in the African ice rat Otomys sloggetti robertsi, a diurnal, herbivorous, non-hibernating murid rodent, endemic to the sub-alpine and alpine regions of the southern African Drakensberg and Maluti mountains. We expected ice rats to be group
living, nesting communally in underground burrows. We documented the spatial organization and social behaviour of free-living ice rats through direct observations and experimental manipulations. Colonies comprised 4–17 adults of both sexes. learn more Members of a colony had a high degree of spatial home-range overlap but no temporal overlap because interactions between members were rare aboveground. Individuals experimentally displaced within their own colony were attacked by members of their own colony and were treated in the same way as strangers from other colonies. Members of a colony competed aggressively for prized food, particularly in winter. Ice rats displayed a vertical spatial separation in social behaviour, from huddling and tolerance belowground to solitary foraging and mutual avoidance aboveground. Such a dichotomy in sociality reflects the compromise between the benefits of social thermoregulation and burrow sharing on the one hand and the constraints of competing for resources, mainly food, on the other.