6.2.1 Diagnosis the Genus Revueltosaurus
The brand new holotypes of Roentgen. callenderi (NMMNH P-4957), “Revueltosaurus” hunti (NMMNH P-29357), together with recently blamed species “Revueltosaurus” (= Pekinosaurus) olseni (YPM 7666; Heckert ainsi que al., 2012 ) per comprise a single remote enamel that has been the cornerstone to own its certain prognosis. Most recently, Heckert et al. ( 2012 ) identified the fresh new genus Revueltosaurus (comprising Roentgen. callenderi, Roentgen. hunti, and you can R. olseni) utilizing the after the mixture of profile claims: dimensions (tooth crowns up to seven in order to fifteen-mm significant); multiple short denticles (more seven for every carina) which can be counterbalance (sub-perpendicular) toward enamel margin; denticles proportionately small and often used into the enamel of the real occlusion; lack of a genuine cingulum; premaxillary tooth crowns that will be as much as doubly significant since the maxillary/dentary tooth crowns and you will weakly recurved; and maxillary/dentary tooth crowns phyllodont (leaf-shaped). grams., Ezcurra, 2016 ). Particularly, the mixture of the measurements of the teeth, how many brand new denticles, and orientation of one’s denticles overlap together with other distantly related taxa (age.grams., Silesaurus opolensis, Dzik, 2003 ; Azendohsaurus madagaskarensis, Flynn mais aussi al., 2010 ). The smoothness “denticles proportionately brief and sometimes worn to your tooth by the particular occlusion” lacks precision when it comes to what exactly is believed “small,” in addition to wear pattern is hard so you can eliminate in other taxa and depends on a particular ages of tooth from inside the replacement period (we.age., younger teeth wouldn’t be diagnosable since there would not be worn). Furthermore, the absence of apomorphic reputation states (elizabeth.grams., lack of cingulum) really should not be included in a diagnosis, as they are symplesiomorphies. While doing so, the fresh assignment of tooth reputation according to one enamel (e.grams., premaxillary enamel crowns is around two times as significant because the maxillary/dentary enamel crowns and you can https://datingranking.net/tr/dominican-cupid-inceleme/ weakly recurved; maxillary/dentary tooth crowns leaf designed) cannot be computed on the brand spanking new method of material, and even with increased teeth regarding exact same area, simply craniodental issue which have teeth offer the latest connection away from enamel profile and you can enamel position. Hence, the brand new suggested enamel standing of your holotype white teeth from K. hunti and P. olseni is believed centered on a keen inferred romantic reference to Roentgen. callenderi, that’s known off craniodental question that have pearly whites (see significantly more than). To conclude, the latest genus Revueltosaurus sensu lato can not be adequately and you may sustainably recognized based on the sort of product from R. callenderi, K. hunti, and you may P. olseni therefore we hence restriction the brand new genus to 1 varieties, R. callenderi. As a result, we suggest that “R”. hunti take care of the personal junior synonym Krzyzanowskisaurus hunti as erected by the Heckert ( 2005 ) and you will “R”. olseni retain the personal older synonym Pekinosaurus olseni. We subsequent alerting the new assignment of any established separated enamel taxa so you can Revueltosaurus.
We would recognize that in the future, with increased done issue, R. callenderi, Krzyzanowskisaurus hunti, and you can Pekinosaurus olseni may show a beneficial monophyletic genus Revueltosaurus, however, a task of the many about three kinds to one genus is not currently it is possible to as it produces an a priori assumption from the dating (get a hold of lower than) that’s parallel into modern argument your Revueltosaurus teeth was indeed assignable in order to Ornithischia in the first place. This may has undesirable streaming outcomes towards after that macroevolutionary education (elizabeth.g., biogeography and you can paleocology). Alternatively, it is reasonably quite possible these particular taxa may begin aside getting distantly associated.
6.dos.dos What is actually Krzyzanowskisaurus hunti?
Heckert ( 2002 ) described “Revueltosaurus” hunti, later assigned to the brand new genus Krzyzanowskisaurus (Heckert, 2005 ), based on separated white teeth in the Los Esteros Member of brand new Santa Rosa Creation (Dockum Classification) in central The Mexico in addition to Bluish Mesa Member of the brand new Chinle Development for the east Arizona (variety of area regarding A good. geoffreyi-discover ), and contains also been recognized from the straight down Chinle Formation in the southeastern Utah ( , p. 16). Krzyzanowskisaurus hunti white teeth is actually notable off Roentgen. callenderi pearly whites of the exposure of a beneficial ridge (“cingulum”) at the base of one’s enamel top, and this links on the carinae which will be commonly denticulated (Heckert, 2002 , 2005 ; Irmis, Parker, et al., 2007 ; Rates 14a, b). Originally, Krzyzanowskisaurus are entitled given the disparate morphology of one’s teeth between both variations and the conflict your Krzyzanowskisaurus white teeth however were assignable to help you an enthusiastic ornithischian instead of an effective pseudosuchian (Heckert, 2005 ). Irmis, Parker, et al. ( 2007 ) disagreed for the project out of Krzyzanowskisaurus hunti towards Ornithischia depending on the equivalent arguments explaining the problems out-of delegating remote pearly whites in order to ornithischians given that exhibited before additionally the build you to definitely Heckert ( 2002 , 2005 ) defined as a “cingulum” wasn’t homologous with the exact same structures during the ornithischian dinosaurs. Also, Irmis, Parker, mais aussi al. ( 2007 ) including detailed one to a Revueltosaurus-for example squamosal, quadrate, and you can osteoderms was in fact together with bought at an equivalent Washington locality just like the Krzyzanowskisaurus hunti white teeth, just as had occurred in the sort of area to possess R. callenderi (Appear mais aussi al., 2005 ).