OCCURRENCE OF THE REGULAR URCHIN EUCIDARIS TRIBULOIDES FROM THE TAMIAMI FORMATION (PLIOCENE) OF FLORIDA ROGER W. PORTELL FLORIDA MUSEUM OF NATURAL HISTORY GAINESVILLE, FLORIDA and CRAIG W. OYEN GEORGIA SOUTHERN UNNERSITY STATESBORO, GEORGIA The echinoids of the Pliocene Tamiami and the echinoids, Echinocardium goth­ Formation of Florida are typically abun­ icum (Ravenel, 1848) and Encope tami­ dant, well-preserved, and reasonably well­ amiensis Mansfield, 1932. Numerous known. In a 1963 monograph, Kier listed pectens and oysters were also collected. All nine species of echinoids from the specimens from UF locality CH026 were Tamiami Formation. These were Arbacia collected in a gray, medium- to fine­ crenulata Kier, 1963, Lytechinus variega­ grained quartz sand with a modest tus plurituberculatus Kier, 1963, Clype­ amount of heavy mineral content. No arag­ aster.crassus Kier, 1963, C. sunnilanden­ onitic-shelled taxa were preserved, only sis Kier, 1963, Encope tamiamiensis calcitic-shelled taxa typically associated Mansfield, 1932, E. michelini imperforata with the Tamiami Formation were present Kier, 1963, Mellita aclinensis Kier, 1963, (see taxa above). At UF locality CH026, Rhyncholampas evergladensis (Mansfield, the Tamiami Formation is overlain by a 2 1932), and Echinocardium gothicum meter thick shell bed attributable to the (Ravenel, 1848). Phelan (1972) eliminated Fort Thompson Formation. previous confusion between E. michelini L. Other fossil occurrences of E. tribuloides Agassiz, 1841, and E. aberrans Martens, are known from outside Florida. Donovan 1867, and re-identified Kier's E. michelini and Embden (1996) summarized t h e imperforata as E. aberrans. Kier (1992) Jamaican occurrences, including speci­ agreed with Phelan's specific assessment mens from the Plio-Pleistocene August but still considered his earlier (1963) sub­ Town Formation, early Pleistocene specific designation to be valid. Since Kier Manchioneal Formation and Old Pera (1963), no new additions to the echinoid Beds, and late Pleistocene Port Morant fauna of the Tamiami Formation have and Falmouth formations. Elsewher e, been reported, until now. Lewis and Donovan (1991) reported radi­ Between 1989 and 1996, fossil collec­ oles from the Pliocene and late Pleistocene tions were made by the Invertebrate of Tobago. Cutress (1980) confirmed sever­ Paleontology staff and volunteers of the al published reports from the Plio­ Florida Museum of Natural History Pleistocene Playa Grande Formation, and (FLMNH) at University of Florida (UF) Pleistocene Abisinia, Cerro Gato, an d locality CH026 (also known as the Tortuga formations of Venezuela. Cutress HandyPhil Pit) in western Charlotte also discounted reports by Jackson (1922) County, Florida (text-figure 1). These col­ and Sanchez Roig (1949) of E. tribuloides lections yielded hundreds of isolated regu­ from the Miocene (?) of Cuba. lar urchin test plates and radioles and Extant E. tribuloides occurs from Cape three partial, but flattened, regular urchin Hatteras, North Carolina, east to tests (UF 39528, UF 60203, and UF Bermuda, throughout the Caribbean, the 72022). Recent analysis of these urchin Gulf of Mexico, and south to Rio de remains ind.icates that they belong to Janeiro, Brazil (Serafy, 1979). Its known Eucidaris tribuloides (Lamarck, 1816), a depth range has been recorded between 0 genus and species not previously recorded and 800 meters. However, it is most com­ from the Florida fossil record. Other com­ monly found at depths of less than 50 mon taxa collected at this locality included meters (Serafy, 1979). Eucidaris tribu­ the brachiopod, Glottidia inexpectans loides inhabit rocky areas, typically under Olsson, 1914; the gastropods, Dicathais rocks and in small crevices. They are also handgenae Portell and Vokes, 1992, and known to inhabit seagrass beds (Hendler Ecphora quadricostata (Say, 1824); the et al., 1995). barnacle, Tamiosoma advena Zullo, 1992; 99 100 Tulane Studies in Geology and Paleontology Vol. 30 cules only modestly larger than surrounding N secondary tubercles. Ambulacra are narrow, slightly sinuous, and widest at ambitus. Poriferous zones in minor, sunken grooves. Pores round to slightly ellipti­ t cal, separated by a low, interporal partition. Ambulacra approximately one-fourth as wide as interambulacra areas. Interambulacra plates up to two times wider HANDYPHIL PIT CHARLOTIE than tall. Interradial tract about two times (CH026) COUNTY wider than adradial tract. Secondary tubercles densely distributed throughout plate surface. Interradial sutur~ simple, non-serrate. · Primary radioles have limited shape varia­ tion, but include both cylindrical and truncate 20 40 km forms. Shaft may be slightly inflated in proxi­ mal to medial portion. Acetabulum diameter · Text Figure 1. Map showing locality of approximately 44-61 % of radiole width. the· first reported occurrence of the fossil Radioles up to 42.9 mm long, and 3.5 to 4.5 mm Eucidaris tribuloides (Lamarck, 1816) wide. Milled ring is located 2.0 to 2.7 mm above from Florida. b-ase, and collar is 1.6 to 2.4 = long with coni­ cal shape widest at milled ring. Neck is narrow ACKNOWLEDGMENTS and located 3.5 to 4.6 mm above base. Shaft has numerous longitudinal series of low nodules, We are indebted to Phillip Whisler of which may not be visible on more poorly pre­ Gainesville, Florida for his assistance in served or altered samples. Distal end ofradioles the field, and particularly, for collecting marked by low-ribbed crown, with a central and donating fossil E. tribuloides speci­ prominence. mens UF 72022 and UF 60203. Jimmy The three flattened tests (UF 72022, UF and Pat Philman, Englewood, Florida, 60203, 39528) are incomplete and compacted; kindly allowed access to their shell pit (UF therefore, not all diagnostic features are well­ locality CH026). Burchard Carter, Georgia preserved. More detailed species descriptions Southwestern State University and are available in Weisbord (1969), Phelan (1970), Stephen Donovan, University of the West Cutress (1980), Donovan (1993), and Hendler et Indies reviewed earlier drafts of the man­ al. (1995). uscript and provided helpful comments. This is University of Florida Contribution Discussion: Comparison of the fossil to Paleontology 486. specimens from the Tamiami Formation with several modern E. tribuloides speci­ mens from the Florida Keys show most SYSTEMATIC PALEONTOLOGY morphologic· characteristics to be similar among the samples. The Florida fossils Class ECHINOIDEA Leske, 1778 also are comparable with E. tribuloides Order CIDAROIDA Claus, 1880 described by Donovan (1993) from the Family CIDARIDAE Gray, 1825 Falmouth Formation (Pleistocene) in Genus EUCIDARIS Doderlein, 1887 Jamaica, as well as samples of this species EuCIDARIS TRIBULOIDES (Lamarck, 1816) reported by Weisbord (1969) from the Plate 1, figures la-b, 2, 3 Playa Grande Formation of Venezuela (Plio-Pleistocene). Many of Weisbord's Description: Test typically flattened both Venezuelan samples are now reposited in adapically and adorally. Primary tubercles non­ the Florida Museum of Natural History crenulate, perforate, having a conical boss near­ and, therefore, were available for compari­ ly circular in outline, and grading into scro­ son by the authors. bicule without a basal terrace. Areoles circular Cutress (1980) compared samples of fos­ at ambitus, becoming transversely elongate sil and modern E. tribuloides collected near apical and oral regions. Scrobicular tuber- from sites in the Caribbean and Gulf of ; No.2 Tamiami Formation Eucidaris 101 Eucidaris tribuloides Biometrics Summary I. Modem Eucidaris tribuioides Number of Plates Mean of Medial Area Mean of Areole Measured Width (MAW) MAW/ArW Width CArW) Ratio Mean n=lS X=2.48mm ir-6.18 mm X=0.40 II. Fossil Eucldaris tribuloides (famiami Formation, Pliocene) Number of Plates Mean of Medial Area Mean of Areole MAW/ArW Measured Width (MAW) Width CArW> Ratio Mean n=20 x=4.32mm x=7.32 mm X=0.58 ArW MAW Text Figure 2. Summary statistics for single-plate measurements of medial area width (MAW), areole width (ArW), and medial area width I areole width ratio (MAW I ArW). Measurements are in mm, and were obtained from locations indicated on the test plate illustration and discussed in the text. (Illustration modified from Cutress, 1980). Mexico region with several fossil and/or ratio of 0.51 for E. clavata and 0.97 for E. modem species of Eucidaris, including E. tribuloid es, while the ApD/P erD mean madrugensis (Sanchez Roig, 1949), E. ratio was 0. 77 for E. clavata and 1.02 for thouarsii (Valenciennes, 1846), and E. E. tribuloides. clauata Mortensen, 1928. Cutress reported Eucidaris thouarsii, a Recent species several key differences between E . tribu­ from the eastern Pacific Ocean, has wider loides and each of these species using both median areas on interambulacral plates qualitative and quantitative (biometric) and wider associated areoles .. Data accu­ characteristics, and we have summarized mulated by Chesher (1972) for the ratio of these differences here. Eucidaris clavata, MAW/ArW of E. tribuloides shows a ratio a modern species known only from range of 0.6-0.8, while on equivalent-sized Ascension and St. Helena Islands in the specimens of E. thouarsii, Cutress (1980) South Atlantic, has fewer interambulacral calculated the mean ratio to be slightly plates per column, contains more conflu­ lower, 0.58, over a range of 0.4-0. 78. An ent areoles, and lacks fan-shaped septal additional biometric ratio, areole width bundles. Biometric analysis of the two (ArW)