The brand new Chinle Development within PEFO is actually really-old from the highest-reliability U–Pb zircon age and you may magnetostratigraphy, demonstrating the whole creation of this type try Norian-Rhaetian when you look at the ages (Kent ainsi que al., 2018 , 2019 ; Ramezani et al., 2011 ; Rasmussen ainsi que al., 2020 ). Roentgen. callenderi takes place in brand new highest Bluish Mesa User thanks to middle Petrified Tree Associate in the PEFO, having a numerical age groups off
No specimens display any signs of scavenging choices
218.5–210 Ma (middle-later Norian; Rasmussen mais aussi al., 2020 ). You will find certain uncertainty on ages of the low area of one’s Sonsela Affiliate according to the years design chose (Rasmussen mais aussi al., 2020 ) but this won’t change the age of the first otherwise history occurrences away from Roentgen. callenderi in the PEFO.
dos.dos Taphonomy
Hundreds of areas of R. callenderi was indeed compiled out-of PFV 297, between busted remote bones so you can partly articulated skeletons. , 2007 ). This new specimens have been every recovered from horizon inside the a greenish-grey mudstone (“blue sites” regarding Loughney ainsi que al., 2011 ) which is adjacent to a channel facies of one’s Coated Desert Sandstone step three (Parker mais aussi al., 2005 ), which most likely show levee places throughout the proximal part of the floodplain (T. Demko, individual interaction, ). Most other vertebrate localities about Petrified Tree Affiliate can be found in this comparable drab-colored bedrooms that happen to be translated as the symbolizing poorly drained paleosols inside the quit station complete that have been at the very least seasonally h2o-saturated (Loughney mais aussi al., 2011 ; Therrien & Fastovsky, 2000 ). Monodominant assemblages aren’t occur in wetland facies (elizabeth.grams., overbank wetland/marginal pond) with low transport and you can reworking prospective (Eberth mais aussi al., 2007 ), and this is consistent with the interpretation of your own depositional environment out of “bluish internet” from Loughney mais aussi al. ( 2011 ). The current presence of fossil equisetalean plants (age.g., PEFO 41412) throughout the quarry plus aids which interpretation. When you look at the several of specimens out-of PFV 297 and PFV 414, the interior areas of your own bone were permineralized by calcite spar, and in some cases, this new skeleton also are overgrown by the a thinner calcite spar level. Of numerous issue enjoys been through moderate plastic deformation and you will brittle distortion since the evidenced of the fracturing https://www.datingranking.net/tr/datehookup-inceleme and you may displacement into the specimens away from much time bones. Or even surface limbs maintenance try exquisite, sustaining okay exterior details (e.g., strength scars) a number of specimens, particularly in PEFO 34561.
The initial point from PFV 297 is actually discovered during the early 2004 and you may compiled primarily given that surface “float” you to definitely eroded from the fossiliferous views, with one in-situ articulated specimen with a limited head (PEFO 33787). Matters away from correct ilia, right femora, and you may remaining frontals conveyed the newest preservation from a minimum of four somebody (Parker et al., 2005 ). Next excavation out-of within the-situ specimens contained many isolated issues and four relevant skeletons (PEFO 34269; PEFO 34561; PEFO 36875; PEFO 36876). PEFO 34561 stands for to 90% of people while offering every description given below. PEFO 36875 features a whole and you can primarily articulated head as well as the a partly articulated postcranial bones. An enthusiastic articulated skull (PEFO 38609) plus one skeleton had been collected in the 2015 (PEFO 42442/UWBM 116869) regarding PFV 414; PEFO 42442/UWBM 116869 saves the brand new vertebral line and you will carapace of the trunk area area within the limited articulation, along with a whole, but hit bottom, skull. These types of skeletons exist since the seemingly isolated density from skeleton regarding unmarried some body elizabeth bed linen airplanes by typically step 1–dos m. Together most of the issue from PFV 297 and you may PFV 414 represents at least twelve some one predicated on femora matters. Mukherjee and you may Ray ( 2012 ) discussed a comparable taphonomic function to possess an effective rhynchosaur-reigned over bonebed about Upper Triassic Tiki Creation out of India. Like with the fresh new Indian assemblage, it is probable on PFV 297 and you may PFV 414, to the fine-grained sediments plus in-situ equisitaleans, you to definitely delicate-muscle decomposition from the shallow-water depth and you may after that weathering processes disarticulated the folks out of R. callenderi. This type of skeletons was later confronted with limited dispersal by the low-energy fluvial agents and finally burial during the floodplain deposits (Mukherjee & Ray, 2012 ). The fresh rareness out of small elements instance gastralia and you will chevrons when you look at the otherwise almost complete specimens, and also the visibility out-of remote skull, girdle, and you will limb skeleton of the same taxon, helps this latter dispersal enjoy (Mukherjee & Beam, 2012 ).
