Journal of Paleontology, 91(4), 2017, p. 579–581 Copyright © 2017, The Paleontological Society 0022-3360/17/0088-0906 doi: 10.1017/jpa.2017.20


Progress in echinoderm paleobiology


Samuel Zamora1,2 and Imran A. Rahman3 1Instituto Geológico y Minero de España (IGME), C/Manuel Lasala, 44, 9ºB, 50006, Zaragoza, Spain ⟨s.zamora@igme.es⟩ 2Unidad Asociada en Ciencias de la Tierra, Universidad de Zaragoza-IGME, Zaragoza, Spain 3Oxford University Museum of Natural History, Parks Road, Oxford, OX1 3PW, United Kingdom ⟨imran.rahman@oum.ox.ac.uk⟩


Echinoderms are a diverse and successful phylum of exclusively marine invertebrates that have an extensive fossil record dating back to Cambrian Stage 3 (Zamora and Rahman, 2014). There are five extant classes of echinoderms (asteroids, crinoids, echinoids, holothurians, and ophiuroids), but more than 20 extinct groups, all of which are restricted to the Paleozoic (Sumrall and Wray, 2007). As a result, to fully appreciate the modern diversity of echinoderms, it is necessary to study their rich fossil record. Throughout their existence, echinoderms have been an


important component of marine ecosystems. Because of their relatively good fossil record, researchers have been able to recon- struct echinoderm diversity through geological time (e.g., Smith and Benson, 2013). Moreover, the echinoderm skeleton is rich in characters for rigorous analyses of disparity, functional morphol- ogy, and phylogeny, providing the means to tackle large-scale evolutionary questions (e.g., Ausich and Peters, 2005; Gahn and Baumiller, 2010; Kroh and Smith, 2010; Deline and Ausich, 2011). Echinoderms are known to modify their physiology, ecol- ogy, and distribution in response to fluctuations in salinity, pH, or temperature, so fossil forms may be useful indicators of past and future environmental change (Aronson et al., 2009). Taken toge- ther, these aspectsmake echinoderms an ideal group for addressing fundamental questions about the history of life on Earth. On June 15–16, 2015, around 50 echinodermologists


(Fig. 1) from 12 different countries attended the Progress in Echinoderm Palaeobiology meeting in Zaragoza, Spain, which was hosted by the Geological Survey of Spain and the


University of Zaragoza. This meeting was followed by a five-day field trip (June 17–21, 2015) that included stops at the most remarkable Paleozoic echinoderm localities in North Spain (Iberian Chains and Cantabrian Mountains) (Zamora et al., 2015). The conference celebrated the career of our colleague and friend Dr. Andrew Smith (Fig. 2), a world-renowned specialist in echinoderms, who retired in late 2012. Andrew spent the majority of his career at the Natural History Museum, London (1982–2012), where he carried out remarkable research on a diverse range of topics, including echinoid taxonomy, Phanerozoic marine diversity, and early fossil echinoderms (Gale, 2015). As a result of the meeting and scientific discussion that took place, we have prepared this special issue in which we combine a series of papers dealing with recent and fascinating advances in echinoderm paleobiology. The issue is divided into six major themes: homology, disparity, trace fossils, functional morphology, systematics, and phylogeny.


Universal elemental homology (UEH) has proven to be one


of the most powerful approaches for understanding homology in early pentaradial echinoderms (Sumrall, 2008, 2010; Sumrall and Waters, 2012; Kammer et al., 2013). This hypothesis focuses on the elements associated with the oral region, identifying possible homologies at the level of specific plates. Two papers, Paul (2017) and Sumrall (2017), deal with the homology of plates associated with the oral area in early pentaradial echinoderms. The former contribution describes and identifies homology in various ‘cystoid’ groups and represents a seminal work for understanding homology among these fossil taxa. The latter paper carefully reviews recent advances in UEH and outlines how this can be applied to representatives of modern echinoderm groups. Both papers provide invaluable data for future research on the relationships of early pentaradial echinoderms. Characterization of the influence of taphonomy on


morphological diversity is crucial for studies that seek to use disparity to address macroevolutionary questions. Deline and Thomka (2017) examine the importance of preservation for quantifying the morphology of Paleozoic echinoderms. They find that estimates of blastozoan disparity are not greatly influenced by the loss of taphonomically sensitive characters, whereas the opposite pattern is seen in crinoids. Since their early history, echinoderms have interacted with


and influenced the sediment in which they lived (Rahman et al., 2009); they can also act as substrates for other organisms, even recording the signal of potential predators. Grun et al. (2017) provide a very detailed analysis of predator-prey inter- actions in various assemblages of the echinoid Echinocyamus stellatus (Capeder, 1906) from the Miocene of Malta. Their study of drilling predation provides critical information about the preferences of predators and serves as an excellent comparison with data obtained from modern ecosystems. Belaústegui et al. (2017) review the extensive record of traces associated with extant and extinct echinoderms. This sheds light on how echinoderm ecology has changed through the Phanerozoic. Reconstructing the function of structures in extinct animals


that lack a clear analogue among extant forms has been a major barrier in paleobiological studies. However, the development of methods for visualizing and analyzing fossils digitally and in three dimensions has transformed the field of functional morphology (Sutton et al., 2014). Waters et al. (2017) use computational fluid dynamics to recreate the function of


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