Cole et al.—New crinoids from the Middle and Upper Ordovician, Spain
cladids, and flexibles (Eckert, 1988; Ausich and Deline, 2012). Although these temporally shifting patterns of faunal composi- tion are well recognized, there is a sampling bias of crinoid occurrence data toward Laurentian faunas. Thus, paleobiogeo- graphic changes in these patterns are less thoroughly char- acterized. In particular, the Katian represents the peak of the early Paleozoic CEF, yet few Gondwanan faunas are known from this interval. This has precluded recognition of any geo- graphic differences in faunal composition. Among Laurentian Katian faunas, the composition of
crinoid assemblages is variable. Although some faunas have a relatively equitable distribution of taxa among clades, in most Laurentian faunas the majority of taxa belong to the disparids or cladids (Table 1). Both diplobathrid and monobathrid camerates are low in diversity in most Katian faunas. Thus, as known from predominantly Laurentian material, the basic clade composition of Katian crinoid faunas had begun to shift toward a composition more similar to faunas of the middle Paleozoic CEF. Until recently, very few Ordovician crinoids described
from crown material were known from Gondwana, and many remain poorly understood taxa (e.g., Vinassa de Regny, 1942; Ubaghs, 1969, 1972). Since 1988, several new faunas have been reported, including crinoids from Argentina (Guensburg and Waisfeld, 2015), France (Lefebvre et al., 2015), Morocco (Donovan and Savill, 1988; Le Menn and Spjeldnaes, 1996; Zamora et al., 2015b), Oman (Donovan et al., 2011), Portugal (Ausich et al., 2007; Correia and Loureiro, 2009), and Spain (Gil Cid et al., 1996, 1998; Ausich et al., 2002, 2007). Of these Ordovician Gondwanan faunas, two are Katian in age. Crinoid taxa known from these Katian Gondwanan faunas include Rosfacrinus Le Menn and Spjeldnaes, 1996 from Morocco and Visocrinus Ausich, Gil Cid, and Domínguez Alonso, 2002 from Spain. Gondwanan Katian faunas with the highest crinoid biodiversity are the Fombuena Formation fauna of Spain, described here, and the Portixeddu Formation fauna of Sardinia. The latter has not yet been formally described, but preliminary work indicates crinoids are relatively diverse, containing anthracocrinid and rhodocrinitid diplobathrids, homocrinid and maennilicrinid disparids, and dendrocrinid cladids (Sumrall et al., 2015).
Fombuena Formation fauna: characteristics and
implications.—Because the Fombuena Formation fauna is the first Katian Gondwanan assemblage from which multiple iden- tifiable crinoid specimens have been recovered, it enhances interpretation of the diversification history, faunal character- istics, and paleoecological constraints of Upper Ordovician Gondwanan faunas. As currently known, the Fombuena Formation has produced six named taxa (four diplobathrid camerates, one monobathrid camerate, and one cladid) and two camerate taxa left in open nomenclature, making it the most diverse Katian age crinoid fauna identified from Gondwana. Most well-sampled Laurentian faunas are dominated by cladids, disparids, or both cladids and disparids. By contrast, the assemblage from the Fombuena Formation is predominantly comprised of camerates; cladids are represented by one taxon and disparids are unknown. This suggests that Katian crinoid faunas of Gondwana may have had a notably different
719
composition and diversification history than those of Laurentia in terms of clade composition. However, improved sampling of the Katian of Gondwana is necessary to further validate this hypothesis. The crinoids recovered from the Fombuena Formation
represent an unexpectedly diverse fauna. The rocks of this formation represent siliciclastic sedimentation in a cool-water environment during the beginning of the Late Ordovician in high-latitude Gondwana. On the basis of the scarcity of crinoid taxa identified from the Middle and Upper Ordovician of Gondwana, these conditions have been cited as factors that potentially limited the diversification of Ordovician Gondwanan crinoid faunas (Lefebvre et al., 2013). Recovery of diverse crinoid material from the Fombuena Formation, however, indicates these factors did not prevent diversification of crinoids in these environments, particularly with respect to camerate crinoids. The diversity of camerate crinoids is particularly notable given the siliciclastic composition of the formation. Camerate crinoids are typically considered to have preferred carbonate environments, a condition inferred to relate to both strategies for substrate attachment and feeding ecology (Ausich, 1985; Kammer and Ausich, 2006), although most studies of preference for carbonate versus siliciclastic environments have focused on Mississippian crinoids. Thus, it does not appear that the Katian camerates of Gondwana had the same environmental limitations as camerate crinoids from later intervals. The crinoid fauna from the Fombuena Formation appears
to represent the beginning of the transition from highly endemic Middle Ordovician faunas to more cosmopolitan Late Ordovi- cian faunas (Lefebvre et al., 2013), which is related to the first pulses of the warming Boda event in Gondwana (Fortey and Cocks, 2005; Zamora et al., 2014). The monobathrid camerate Eopatelliocrinus, which was previously known only from Laurentia, is now recognized as a more cosmopolitan genus based on the description of E. hispaniensis, n. sp. Although endemic, three of the four diplobathrid camerates belong to the family Anthracocrinidae, which was previously known from only a few Laurentian specimens. Ausich and Deline (2012) concluded that the more cosmopolitan Silurian faunas had their phylogenetic roots in Ordovician lineages from North America, and it appears that the Fombuena Formation crinoids may also be closely linked with Laurentian faunas. The cladid Picassocrinus n. gen. n. sp., however, has a unique morphology among Ordovician crinoids and represents a genus that is currently unknown outside Gondwana. Whereas Katian faunas in Laurentia had already begun to transition to the composition of middle Paleozoic CEFs (i.e., more cladids and monobathrid camerates and fewer diplobathrid camerates), the Fombuena fauna is still very much dominated by diplobathrid camerate crinoids. This suggests the transition from the early to the middle Paleozoic CEF was asynchronous across the globe.
Systematic paleontology
The suprageneric classification used here is from Moore & Teichert (1978) and Ausich (1998a, 1998b). Morphological terminology follows Ubaghs (1978). The plating in the interrays is given as the number of plates in each range from the proximal- most plate to the last range before the tegmen. In the posterior
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