Triassic nursery? Evidence of gregarious behavior in juvenile pseudosuchian archosaurs as inferred by humeral histology of Aetosaurus ferratus (Norian; southern Germany)

Palaeobiological inferences of “rauisuchians” Fasolasuchus tenax (Los Colorados Fm., Argentina) and Prestosuchus chiniquensis (Santa Maria Super sequence, Brazil) from the Middle–Upper Triassic of South America based on microstructural analyses

“…Furthermore, despite the particular microstructural preservation conditions between the femur and the rib, there seems to be a notable difference in the growth mode of both bones. A similar growth difference was observed in the humerus and femur of the aetosaur Stagonolepis olenkae (Teschner, Konietzko‐Meier, Desojo, et al, 2022; Teschner, Konietzko‐Meier, & Klein, 2022). The femur of F. tenax PVL 3850, despite lacking a portion of the cortex, does not show the extensive signs of bone remodelling (i.e., into Haversian bone) seen in the rib.…”

“…In a broader phylogenetic frame, focusing on the Pseudosuchia and excluding Crocodylomorpha, the growth rate of Fasolasuchus tenax and other “rauisuchians” seems relatively higher than that of aetosaurs (e.g., Aetosaurus ferratus , Aetosauroides scagliai , Coahomasuchus chathamensis , Stagonolepis olenkae ), phytosaurs (e.g., Rutiodon , Mystriosuchus steinbergeri , Parasuchus sp. ), erpetosuchids (MCZ 4077), ornithosuchids ( Ornithosuchus ) and some non‐Loricata Paracrocodylomorpha ( Mandasuchus tanyauchen ) (Butler et al, 2017, 2019; de Ricqlès et al, 2008; Ponce et al, 2022; Teschner, Konietzko‐Meier, Desojo, et al, 2022; Teschner, Konietzko‐Meier, & Klein, 2022). Despite the relatively higher rate of growth in comparison with all these clades, “rauisuchians” do not possess a specific and typical growth pattern because, although an overall rapid mode of growth is shown (except for P. chiniquensis ), there is some variation recorded.…”

Incongruent ontogenetic maturity indicators in a Late Triassic archosaur (Aetosauria: Typothorax coccinarum)

“…The posteromedial region of the proximal sample (Figure 3d; where the LAGs are preserved) shows no evidence of high vascularity or high levels of disorganization (i.e., woven bone tissue) which are suggestive of fast growth (de Boef & Larsson, 2007; de Buffrénil & Quilhac, 2021; Parker et al, 2021). Previous histological studies (e.g., Cerda et al, 2018; Cerda & Desojo, 2011; de Ricqlès et al, 2021; Hoffman et al, 2019; Paes‐Neto et al, 2021; Parker et al, 2008; Ponce et al, 2023; Scheyer et al, 2014; Taborda et al, 2013; Teschner et al, 2022, 2023; Werning, 2013) sampling aetosaur limbs and osteoderms arrived at the same interpretations, suggesting that aetosaurs exhibited growth rates similar to extant crocodylians (de Ricqlès et al, 2003; Parker et al, 2008) or possibly even slower (Taborda et al, 2013). Recent histological studies found that some aetosaurs (i.e., Coahomasuchus chathamensis ; Aetosauroides scagliai = “ Polesinosuchus aurelioi ”; typothoracine juvenile specimen, GR 252) exhibited periods of rapid bone deposition as indicated by the presence of woven‐fibered bone tissue (Hoffman et al, 2019; Paes‐Neto et al, 2021; Ponce et al, 2023; Werning, 2013), suggesting a disparity in growth rates within the Aetosauria.…”

New fossils, new ideas: selected contributions of vertebrate paleontology to scientific knowledge

“…In "Triassic nursery? Evidence of gregarious behavior in juvenile pseudosuchian archosaurs as inferred by humeral histology of Aetosaurus ferratus (Norian; southern Germany)," Teschner et al (2023) investigated an assemblage of 24 aetosaur individuals that were found in close proximity in a deposit that showed little signs of transport. The osteohistology of the largest and smallest individuals was investigated, and despite their four-fold difference in size, they were both less than a year old at death and preserved bone tissue that would have been deposited around the time of hatching.…”

“…The osteohistology of the largest and smallest individuals was investigated, and despite their four-fold difference in size, they were both less than a year old at death and preserved bone tissue that would have been deposited around the time of hatching. Teschner et al (2023) surmise that the 24 individuals may represent a clutch that stayed together for an extended period of time, with strong intraspecific variation in growth rates. The social lives of this ephemeral but important clade will likely draw increased attention for some time to come.…”