- Haramiyida
Taxobox
image_width=200px
name = Haramiyida
fossil_range =Jurassic -Oligocene
regnum =Animal ia
phylum =Chordata
classis =Mammalia
ordo =Multituberculata
subordo = Haramiyada
subordo_authority =Hahn ,Sigogneau -Russell &Wouters , 1989 (incl.Eleutherodontida Kermack et al., 1998)
subdivision_ranks = Superfamily
subdivision =
*†Theroteinoidea
*†Haramiyoidea Haramiyidans seem to be the earliest known
herbivore s amongst basalmammal s, assuming they are mammals. Their teeth, which are by far the most common remains, resemble those of themultituberculate s. The jaw however, based onHaramiyavia , is less derived; "at the level of evolution of Morganucodon and Kuehneotherium, with a groove for ear ossicles on the dentary" (Butler PM, 2000).It is tempting to infer that this order represents the ancestors of the
multituberculates , a group which appears to have survived until about 40 million years ago. Whilst this is not impossible, the evidence available is insufficient to be conclusive. As an illustration and with reference to material from Greenland: "Jenkins' group identified haramiyid jaws with the teeth in place, as well as additional parts of the skeleton. Among other revelations from the fossils, the teeth in the upper jaw do not fit the classic multituberculate arrangement, with the second molar offset towards the centre of the mouth."That shows rather well that haramiyids are not closely related to multituberculates," says William A. Clemens of the
University of California, Berkeley , one of the leaders of the multituberculate symposium," (Monastersky 1996, p.379). This taxon is in some disgrace for beingparaphyletic , (Butler & Hooker 2005, p.185). It doesn't consist of one ancestor and all of its descendants. Kemp, 2005 (p.140-141) provides a concise overview of the post-canine s. Harami Molars are larger than many of their equivalents from contemporary mammals, but not by much. These have many of cusps and are generally double-rooted. The crowns are wide and have a line of three large cusps on one edge, with five smaller ones on the opposing side.Originally, it was thought that upper and lower molars were pretty much mirror images of each other, and minor details lead to the establishment of two genera:
Thomasia and Haramiya. The suggestion was subsequently made that these could also represent lowers and uppers of only one genus, and the discovery of Haramiyavia provided confirmation for that. The teeth of Theroteinida and Eleutherodontida, (nothing more is yet known), are perhaps more accurately described as 'haramiyidan'-like. "But haramiyids are known from beds as old as Norian: hence, if they are related to multituberculates, an astonishingly early divergence of crown mammals (not to mention a series of putative sister taxa to crown mammals) is implied," (Cifelli, 2001).More precise affinities will probably remain unclear until better evidence is forthcoming. Butler & Hooker, (2005) maintain that 'haramiyids' are still stronger candidates for having given rise to the multituberculates than
morganucodontid s are: "As long as we only have teeth to of the critical taxa, we feel it necessary to adopt theAllotheria concept as a working hypothesis; no doubt the discovery of mammalian skeletal material in theJurassic will throw new light on the problem", (p.206). The concept of Allotheria unites haramis and multituberculates as the sister line of other mammals.Most fossils have been reported from Europe, but some are known from Africa and Greenland. A description in January 2005 extended the published range to the Junggar Basin of Inner Mongolia. It may be safer to refer to this group as haramyioidens rather than 'haramiyidans'. 'Haramiyan' fossils first appear in the Upper
Triassic . Until 1999, the last traces were Middle Jurassic. However,Allostaffia then turned up in the Upper Jurassic ofTanzania .Links
*Palaeos, Mammaliaformes: Allotheria - [http://www.palaeos.com/Vertebrates/Units/Unit420/420.100.html]
*John H Burkitt, Mammals, A World Listing of Living and Extinct Species - [http://cougarhillweb.org/mammals.pdf]
*T Mike Keesey, The Dinosauricon, Ages of the Mesozoic - [http://www.dinosauricon.com/times/index.html]
*Mikko K Haaramo, Haramiyida - [http://www.fmnh.helsinki.fi/users/haaramo/Metazoa/Deuterostoma/Chordata/Synapsida/Basal_Mammalia/Allotheria/Haramiyida.htm]
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