The fresh new Chinle Formation within PEFO has started to become really-dated by high-accuracy U–Pb zircon age and magnetostratigraphy, exhibiting your whole creation in this area is Norian-Rhaetian for the many years (Kent mais aussi al., 2018 , 2019 ; Ramezani et al., 2011 ; Rasmussen et al., 2020 ). Roentgen. callenderi happens in the latest best Bluish Mesa User as a consequence of center Petrified christianmingle profil arama Tree Representative within PEFO, which have a mathematical age groups away from
Zero specimens display people signs and symptoms of scavenging conclusion
218.5–210 Ma (middle-later Norian; Rasmussen et al., 2020 ). There is particular uncertainty regarding age of the low part of the Sonsela Representative with regards to the many years design picked (Rasmussen ainsi que al., 2020 ) however, it doesn’t affect the age of the first or history occurrences out of Roentgen. callenderi at PEFO.
dos.2 Taphonomy
Countless components of Roentgen. callenderi had been compiled away from PFV 297, anywhere between busted isolated bones so you’re able to partly articulated skeletons. , 2007 ). The specimens have been all recovered in one views during the an excellent greenish-grey mudstone (“bluish sites” off Loughney mais aussi al., 2011 ) which is next to a funnel facies of Painted Desert Sandstone 3 (Parker mais aussi al., 2005 ), hence probably represent levee deposits regarding proximal part of the floodplain (T. Demko, individual telecommunications, ). Other vertebrate localities about Petrified Forest Associate can be found contained in this equivalent drab-coloured beds that happen to be translated while the representing poorly drained paleosols from inside the abandoned route complete that have been about seasonally liquid-saturated (Loughney mais aussi al., 2011 ; Therrien & Fastovsky, 2000 ). Monodominant assemblages commonly occur in wetland facies (age.g., overbank wetland/marginal pool) with lower transport and you will reworking potential (Eberth ainsi que al., 2007 ), and this is consistent with the translation of your own depositional environment out of “blue websites” off Loughney ainsi que al. ( 2011 ). The existence of traditional equisetalean flowers (elizabeth.g., PEFO 41412) about quarry also helps this interpretation. From inside the several of specimens from PFV 297 and you can PFV 414, the internal spaces of your bone were permineralized because of the calcite spar, and in many cases, the skeleton are overgrown by a slimmer calcite spar level. Of many elements has actually experienced limited vinyl deformation and brittle distortion due to the fact confirmed by fracturing and you will displacement inside the specimens away from enough time bones. Otherwise skin bones maintenance is superb, sustaining great outside information (elizabeth.grams., strength markings) in several specimens, especially in PEFO 34561.
The first issue out of PFV 297 is actually located at the beginning of 2004 and accumulated generally as the body “float” one to eroded out from the fossiliferous opinions, having one in-situ articulated sample having a limited skull (PEFO 33787). Counts away from correct ilia, best femora, and you can kept frontals expressed the preservation off at least four anybody (Parker et al., 2005 ). Then excavation out-of inside-situ specimens consisted of many remote elements also four relevant skeletons (PEFO 34269; PEFO 34561; PEFO 36875; PEFO 36876). PEFO 34561 means to 90% of men and women while offering all of the description given below. PEFO 36875 features a whole and you may mainly articulated skull too as the a partly articulated postcranial skeleton. An articulated skull (PEFO 38609) and something bones was indeed gathered inside 2015 (PEFO 42442/UWBM 116869) out of PFV 414; PEFO 42442/UWBM 116869 saves the latest vertebral column and you will carapace of the trunk area region inside limited articulation, plus a complete, however, flattened, head. These types of skeletons occur due to the fact seemingly isolated levels out of bones out-of single someone age bedding jet by typically step 1–dos m. With her the thing out-of PFV 297 and you may PFV 414 represents a minimum of several some one centered on femora counts. Mukherjee and Ray ( 2012 ) explained a comparable taphonomic means to have an excellent rhynchosaur-dominated bonebed from the Upper Triassic Tiki Formation off Asia. Just as in the newest Indian assemblage, it is probable within PFV 297 and you may PFV 414, toward okay-grained sediments plus-situ equisitaleans, you to silky-cells decomposition in the shallow-water depth and you may next weathering process disarticulated the folks from R. callenderi. These skeletons was after confronted with limited dispersal from the low energy fluvial representatives and ultimately burial in the floodplain dumps (Mukherjee & Ray, 2012 ). The fresh rarity of short facets such as gastralia and you can chevrons from inside the if you don’t almost complete specimens, as well as the presence off separated skull, girdle, and you may limb skeleton of the same taxon, helps it latter dispersal enjoy (Mukherjee & Ray, 2012 ).