DOI: 10.5061/dryad.qc86g11
title: Data from: Bone histology of Azendohsaurus laaroussii. Implications for the evolution of thermometabolism in Archosauromorpha

description: 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.
description: Supplementary Figure
 1Supplementary 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 mmSupplementary Figure
 2Supplementary 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
 3Supplementary 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.Legends of Supplementary
 FiguresLegends of Supplementary
 Figures