Data from: Bone histology of Azendohsaurus laaroussii. Implications for the evolution of thermometabolism in Archosauromorpha

Cubo, Jorge, Sorbonne University

Jalil, Nour-Eddine, Cadi Ayyad University

Published Feb 25, 2019 on Dryad. https://doi.org/10.5061/dryad.qc86g11

Cite this dataset

Cubo, Jorge; Jalil, Nour-Eddine (2019). Data from: Bone histology of Azendohsaurus laaroussii. Implications for the evolution of thermometabolism in Archosauromorpha [Dataset]. Dryad. https://doi.org/10.5061/dryad.qc86g11

Abstract

This paper is aimed at constraining the phylogenetic frame of the acquisition of endothermy by Archosauromorpha. We analyzed the bone histology of Azendohsaurus laaroussii. Stylopodial and zeugopodial bones show three tissue types: (a) avascular lamellar zonal bone formed at low growth rates; (b) a scaffold of parallel fibered bone containing either small primary osteons or simple vascular canals; and (c) fibrolamellar bone formed at high growth rates. We used quantitative histology to infer the thermometabolic regime (endothermy versus ectothermy) of this taxon. We define endothermy as the presence of any mechanism of non-shivering thermogenesis that increases both body temperature and resting metabolic rate. Thus, estimating the resting metabolic rate of an extinct organism may be a good proxy to infer its thermometabolic regime (endothermy versus ectothermy). High resting metabolic rates have been shown to be primitive for the clade Prolacerta – Archosauriformes. Therefore, we inferred the resting metabolic rates of Azendohsaurus laaroussii, a sister group of this clade, and of 14 extinct related taxa, using Phylogenetic Eigenvector Maps. All the inferences obtained are included in the range of variation of resting metabolic rates measured in mammals and birds, so we can reasonably assume that all these taxa (including Azendohsaurus) were endotherms. A parsimony optimization of the presence of endothermy on a phylogenetic tree of tetrapods shows that this derived character state was acquired by the last common ancestor of the clade Azendohsaurus – Archosauriformes, and that there is a reversion in Crocodylia.

Usage notes

Supplementary Figure 1

Supplementary FIGURE 1. Composite images of entire diaphyseal cross sections of right humerus MNHN.F ALM435, left femur MNHN.F ALM497 and right tibia MNHN.F ALM369. Abbreviations: A, anterior; D, dorsal; L, lateral; M, medial; P, posterior; V, ventral. Scale bar: 1 mm

Supplementary Figure 2

Supplementary FIGURE 2. Optimization using parsimony of the presence of fibrolamellar bone in the stylopodial and zeugopodial bones of the Archosauromorpha analyzed to date (data summarized in Table 1). The topology is based on Nesbitt et al (2009) for Archosauriformes, and on Pritchard et al (2015) for non-archosauriform Archosauromorpha with the exception of the phylogenetic position of Aenigmastropheus parringtoni that has been taken from Ezcurra et al (2014). The minimum age of taxa has been taken from the Paleobiology Database. Black branches indicate presence of fibrolamellar bone, white branches indicate absence and black and white branches indicate uncertain character state.

Supplementary Figure 3

Supplementary FIGURE 3. Optimization using parsimony of the presence of fibrolamellar bone in the stylopodial and zeugopodial bones of the Archosauromorpha analyzed to date (data summarized in Table 1). The topology is based on Nesbitt et al (2009) for Archosauriformes, and on Ezcurra (2016) for non-archosauriform Archosauromorpha with the exception of the phylogenetic position of Aenigmastropheus parringtoni that has been taken from Ezcurra et al (2014). The minimum age of taxa has been taken from the Paleobiology Database. Black branches indicate presence of fibrolamellar bone, white branches indicate absence and black and white branches indicate uncertain character state.