DOI: 10.5061/dryad.2t30k
title: Data from: Empirical and theoretical study of Atelostomate (Echinoidea, Echinodermata) plate architecture: using graph analysis to reveal structural constraints

description: Describing patterns of connectivity among organs is essential for
 identifying anatomical homologies among taxa. It is also critical for
 revealing morphogenetic processes and the associated constraints that
 control the morphological diversification of clades. This is particularly
 relevant for studies of organisms with skeletons made of discrete elements
 such as arthropods, vertebrates, and echinoderms. Nonetheless, relatively
 few studies devoted to morphological disparity have considered
 connectivity patterns as a level of morphological organization or
 developed comparative frameworks with proper tools. Here, we analyze
 connectivity patterns among apical plates in Atelostomata, the most
 diversified clade among irregular echinoids. The clade comprises
 approximately 1600 fossil and Recent species (e.g., 25% of post-Paleozoic
 species of echinoids) and shows high levels of morphological disparity.
 Plate connectivity patterns were analyzed using tools and statistics of
 graph theory. To describe and explore the diversity of connectivity
 patterns among plates, we symbolized each pattern as a graph in which
 plates are coded as nodes that are connected pairwise by edges. We then
 generated a comparative framework as a morphospace of connections, in
 which the disparity of plate patterns observed in nature was mapped and
 analyzed. Main results show that apical plate patterns are both highly
 disparate between and within atelostomate groups and limited in number;
 overall, they also constitute small, compact, and simple structures
 compared to possible random patterns. Main traits of the evolution of
 apical plate patterns reveal the existence of strong morphogenetic
 constraints that are phylogenetically determined. In contrast,
 evolutionary radiations within atelostomates were accompanied by a clear
 increase in disparity, suggesting a release of some constraints at the
 origin of clades.
description: Supplementary Table
 1Observed contact
 incidences between apical plate pairs in echinoids along with topological
 index values. Abbreviations: OUT, outgroup representing the regular
 pattern; BI, basal Irregularia; BA, basal Atlostomata; H, Holasteroida; S,
 Spatangoida. EJ, Early Jurassic (Liassic); MJ, Middle Jurassic; LJ, Late
 Jurassic; EC, Early Cretaceous; LC, Late Cretaceous; PN, Paleogene and
 Neogene; P, Present day. OI to OV, ocular plates 1 to 5; G1 to G5, genital
 plates 1 to 5. Apical systems of reference specimens are from the
 literature and from specimens observed in collections. Collection
 specimens are from private collections: Clavel, Courville, Fournier,
 Vadet, and Votat. Collection specimens from academic collections are from:
 University of Burgundy, Dijon, France (UB), National History Museum,
 London, UK (NHM), Museum of Comparative Zoology, Harvard University, Mass.
 (MCZ), Museu de Geologia, Barcelona, Spain (MGB), Muséum National
 d'Histoire Naturelle, Paris, France (MNHN), University of California
 Museum of Paleontology, Berkeley (UCMP), Saint-Petersburg State
 University, Russia (SPU), University of Toulouse, France (UT), National
 Museum of Natural History, Smithsonian Institution, Washington, D.C.
 (USNM), Institute of Paleobiology of Polish Academy of Sciences in Warsaw,
 Poland (PAS), Sedgwick Museum of Earth Sciences, University of Cambridge,
 UK (SM), Museum of Lyon, France (ML), Paleontological Institute of the
 Russian Academy of Sciences, Moscow, Russia (RAS), Département de Géologie
 de la Faculté des Sciences d’Agadir, Morocco (MAS), Museum of Grenoble,
 France (MG).Supplementary
 AppendixElements of proof on the
 ranges of the topological indexes used to characterize plate
 architectures, considering n&gt;3.