Hematological convergence between Mesozoic marine reptiles (Sauropterygia) and extant aquatic amniotes elucidates diving adaptations in plesiosaurs

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Paleontology and Evolutionary Science

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Introduction

Materials and methods

Fossil sample base

Measurement and inference of eosauropterygian RBC size

RBC and body mass parameters in extant taxa

Results

Red blood cell size in Eosauropterygia

Body mass and RBC size in extant reptiles

RBC size and aquatic adaptation in extant taxa

Discussion

Methodological issues

RBC size evolution in eosauropterygians: effects of body mass, genome size and metabolic rate

Adaptive significance of secondarily enlarged RBCs in plesiosaurs and other marine amniotes

Conclusions

Supplemental Information

Red blood cell size (area (µm2) or length (µm)) regressed against body mass in selected reptilian groups investigated for the study.

A: Lacertidae (n = 21, adjusted R2 = 0.218, p = 0.02). B: Colubridae (n = 42, adjusted R2 = −0.018, p = 0.48). C: Testudines (n = 31, adjusted R2= 0.488, p = 0.02).

DOI: 10.7717/peerj.8022/supp-1

Minimum vascular canal caliber in 13 eosauropterygian species, used as predicting variables to estimate red blood cell size.

DOI: 10.7717/peerj.8022/supp-2

Statistics of the model to predict red blood cell area.

t value refers to the t-rest of the respective line in the table. Pr(>|t|) is the p value for the t-test. V_1 is the selected vector of the model. The adjusted R2 of the model is 0.8799. The F statistic of the overall analysis is 48.6 on 2 and 11 degrees of freedom with a p value of 3.463e−06. The AICc of the model including minimum canal caliber as a predicting variable is 11.4738. The AICc of the model including phylogeny only is 16.1778. The steepness parameter was estimated to be a = 0.6408827.

DOI: 10.7717/peerj.8022/supp-3

Statistics of the model to predict red blood cell width.

t value refers to the t-rest of the respective line in the table. Pr(>|t|) is the p value for the t-test. V_7, V_10 and V_1 are the selected vectors of the model. The adjusted R2 of the model is 0.8586. The F statistic of the overall analysis is 20.7 on 4 and 9 degrees of freedom with a p value of 0.0001452. The AICc of the model including minimum canal caliber as a predicting variable is −7.466441. The AICc of the model including phylogeny only is −8.148751. The steepness parameter was estimated to be a = 0.5479073.

DOI: 10.7717/peerj.8022/supp-4

Red blood cell area with 95% confidence intervals estimated from vascular canal caliber while taking into account phylogenetic relationships.

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Red blood cell width with 95% confidence intervals estimated from vascular canal caliber while taking into account phylogenetic relationships.

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Hematological data of extant reptiles used.

All measurements are given in µm. Names listed have been checked to comply with current taxonomic nomenclature and for this reason might deviate from the ones listed in the referenced literature.

DOI: 10.7717/peerj.8022/supp-7

Maximum body masses (g) of reptiles for which hematological data is given in Table S6.

Names listed have been checked to comply with current taxonomic nomenclature and for this reason might deviate from the ones listed in the referenced literature.

DOI: 10.7717/peerj.8022/supp-8

Data on mammalian red blood cell volumes (µm3) compiled from the literature.

When studies presented data of several individuals or populations those were averaged before the inclusion into the table. Names listed have been checked to comply with current taxonomic nomenclature and for this reason might deviate from the ones listed in the referenced literature. *Only values for adults were used although data for juveniles were given; **Study only investigated juveniles ***Values from wild caught individuals were used.

DOI: 10.7717/peerj.8022/supp-9

Data on avian red blood cell volumes (µm3) compiled from the literature.

When studies presented data of several individuals or populations those were averaged before the inclusion into the table. Names listed have been checked to comply with current taxonomic nomenclature and for this reason might deviate from the ones listed in the referenced literature.

DOI: 10.7717/peerj.8022/supp-10

Phylogenetic framework for RBC parameter estimation.

DOI: 10.7717/peerj.8022/supp-11

Supplemental References.

DOI: 10.7717/peerj.8022/supp-12

Additional Information and Declarations

Competing Interests

The authors declare that they have no competing interests.

Author Contributions

Corinna V. Fleischle conceived and designed the experiments, performed the experiments, analyzed the data, prepared figures and/or tables, authored or reviewed drafts of the paper, approved the final draft, performed statistical modelling.

P. Martin Sander performed the experiments, contributed reagents/materials/analysis tools, authored or reviewed drafts of the paper, approved the final draft.

Tanja Wintrich performed the experiments, contributed reagents/materials/analysis tools, approved the final draft, revised the manuscript.

Kai R. Caspar conceived and designed the experiments, performed the experiments, analyzed the data, prepared figures and/or tables, authored or reviewed drafts of the paper, approved the final draft, compiled biometric datasets on extant taxa.

Data Availability

The following information was supplied regarding data availability:

Original measurements and statistical notes as well as published biometric data analyzed are available in the Supplemental Files.

All petrographic thin-sections used in the study are housed at the Section Paleontology, Institute of Geosciences, Universität Bonn, Bonn, Germany, as part of the research collection of the Sander lab.

Accession numbers are as follows (one specimen per species was used):

Anarosaurus heterodontus: NMNHL Wijk. 06-38fe

Neusticosaurus edwardsii: PIMUZ T3455

Neusticosaurus peyeri: PIMUZ T 4089

Neusticosaurus pusillus: PIMUZ T 3566

Nothosaurus sp.: IGWH 21

Cymatosaurus sp.: IGWH 6

Pistosaurus longaevus: SMNS 84825

Cryptoclidus eurymerus: IGPB R 324

Elasmosauridae indet.: OMNH MV 85

Plesiosaurus dolichodeirus: IGPB R90

Pliosaurus sp.: SMNS 96896

Polycotylus latipinnus: LACM 129639A

Rhaeticosaurus mertensi: LWL MfN P 64047

Funding

Funding was provided by the German Research Foundation (grant no. SA 469/47-1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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