Soft tissue characteristics for the reconstruction of ruminant phylogeny.
In: Zitteliana, Vol. B 32: S. 33-46
In the attempt to derive phylogenetic relationships from the most comprehensive of character matrices, not only molecular, biochemical and osteological, but also data from less frequently used domains such as behaviour, life history, physiology and soft tissue anatomy are sought. Here, soft tissue traits that have been used in ruminant phylogenetic analyses, and that are potentially available for such analyses, are reviewed. The use of certain measures, such as the presence of an ileocaecal gland or certain skin glands, or the number of colic coils, appears unfounded. Using the presence of the gall bladder as a family trait disregards notable exceptions in the Bovidae. The largest set of potential, easily available soft tissue data appears to be related to the digestive tract, but has so far not been utilized. Generally, the paucity of recent anatomical studies is striking, which means that many available anatomical reports or drawings stem from the beginning of the 20th century. Currently no dataset exists that describes soft tissue anatomy for various organ systems in the same specimens (as is standard for osteological traits taken from whole skeletons). Suggestions are presented how data evaluation and scoring can be performed avoiding circular reasoning, and a plea is made for using data on a species, not a family level. The importance of assessing data independence and correcting for body mass-related effects is emphasized. For most organ systems, new, coordinated, systematic dissections are necessary before a reliable inclusion of soft tissue traits will become possible.