DOI: 10.5061/dryad.h70rxwdz1
title: Data from: Filling a key gap in growth patterns of Pseudosuchia through the osteohistology of <em>Dynamosuchus collisensis</em> (Ornithosuchidae: Archosauria)

description: Ornithosuchidae are among the least studied pseudosuchians from a
 histological perspective, and their life history remains poorly
 constrained. Here we present the first long-bone osteohistological data
 for the Brazilian ornithosuchid Dynamosuchus collisensis, based on
 mid-diaphyseal thin sections of the humerus and femur, supplemented by a
 rib. The long bones show cortices dominated by highly vascularised
 woven-parallel complex and parallel-fibred bone, with three well-defined
 annuli and a fourth incipient one near the periosteal margin. Medullary
 expansion occurs through endosteal resorption, and secondary osteons are
 absent. The rib displays lower vascularisation, consistent with reduced
 growth rates in axial elements. Open neurocentral sutures, the absence of
 an EFS, and the lack of peripheral slowdown in cortical deposition
 indicate that the holotype was skeletally and likely sexually immature.
 These features support sustained rapid growth, contrasting with the
 predominantly slow growth of late-diverging crocodylomorphs and more
 closely resembling early loricatans and poposauroids. Because
 Ornithosuchidae occupy an early-diverging position within Pseudosuchia,
 these data are consistent with the hypothesis that fast growth may
 represent a plesiomorphic condition within the clade. If the holotype was
 not fully grown, Dynamosuchus collisensis may have attained larger body
 sizes and acted as a top-tier predator in Carnian ecosystems.
description: Histological samples were prepared following standard
 paleohistological protocols for fossil bone. Elements were embedded in
 resin, sectioned using a precision diamond saw, and mounted on glass
 slides before being ground to optical translucency. Imaging was performed
 on polished thin sections under polarizing light microscopy, using
 high-resolution tiled captures subsequently stitched into panoramas for
 microstructure interpretation. Data include high-resolution thin-section
 raw panorama images necessary to reproduce the qualitative interpretations
 presented in the accompanying manuscript. For the femur, the raw images
 are provided under normal transmitted light; polarised images shown in the
 manuscript were produced from the same thin-section locally and do not
 constitute additional raw data.
description: # Data from: Filling a key gap in growth patterns of Pseudosuchia through
 the osteohistology of *Dynamosuchus collisensis* (Ornithosuchidae:
 Archosauria) Dataset DOI:
 [10.5061/dryad.h70rxwdz1](https://doi.org/10.5061/dryad.h70rxwdz1) ##
 Description of the data and file structure This dataset contains raw
 panoramic osteohistological images of a humerus, a femur, an indeterminate
 long bone and a rib belonging to CAPPA/UFSM 0248 (*Dynamosuchus
 collisensis*). The panoramas were automatically generated by *Affinity
 Photo 2* (macOS) ### Files and variables #### File:
 RSOS-252042_humerus_polarised.jpg **Description:** high-resolution
 polarised panoramic thin-section of the humerus. #### File:
 RSOS-252042_femur.jpg **Description:** high-resolution panoramic
 thin-section of the femur. #### File: RSOS-252042_femur_polarized.jpg
 **Description:** high-resolution polarised magnified view of thin-section
 of the femur. #### File: RSOS-252042_indeterminate_long_bone_polarised.jpg
 **Description:** high-resolution polarised panoramic thin-section of the
 indeterminate long bone. #### File: RSOS-252042_rib_polarised.jpg
 **Description:** high-resolution polarised panoramic thin-section of the
 rib. #### ## Code/software The images can be opened with any standard
 image viewer. ## Access information Other publicly accessible locations of
 the data: * not applicable. Data was derived from the following sources: *
 not applicable.