Journal of South American Earth Sciences 74 (2017) 67e82 Contents lists available at ScienceDirect Journal of South American Earth Sciences journal homepage: www.elsevier.com/locate/jsames Paleocene decapod Crustacea from northeastern Mexico: Additions to biostratigraphy and diversity Jose Luis Martínez-Díaz a, Martha Carolina Aguillon-Martínez b, Javier Luque c, d, Francisco J. Vega e, * a Posgrado en Ciencias Biologicas, Instituto de Geología, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, Coyoacan, 04510, Mexico, DF, Mexico b Secretaría de Educacion y Cultura, Museo del Desierto, Departamento de Paleontología, Prol. Perez Trevino~ 3745, Parque las Maravillas, Saltillo, Coahuila, 25015, Mexico c Department of Biological Sciences, University of Alberta, Edmonton, Alberta, T6G 2E9, 29, Canada d Smithsonian Tropical Research Institute, BalboaeAncon, 0843e03092, Panama, Panama e Instituto de Geología, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, Coyoacan, 04510, CdMx, Mexico article info abstract Article history: New decapod specimens from mid-Paleocene shallow marine deposits of NE Mexico represents an Received 21 November 2016 important addition to the diversity, paleobiogeography and evolution of the Crustacea record. In this Received in revised form work, we describe additions to the decapod assemblage from the Paleocene (Selandian) Rancho Nuevo 2 January 2017 Formation (Difunta Group, Parras Basin, Coahuila). Due to the evident size differences with other Accepted 10 January 2017 decapod assemblages, we compare the new assemblage with those from the Lower Paleocene (Danian) Available online 11 January 2017 Mexia Clay Member of the Wills Point Formation, Texas, and the Lower Eocene (Ypresian) El Bosque Formation in Chiapas. Species reported from the mid-Paleocene (Selandian) assemblage of the Porters Keywords: Crustacea Creek Formation (Alabama), are correlatable to the decapod species from NE Mexico in age, size and Decapoda systematic composition. The erymid lobster Enoploclytia gardnerae (Rathbun, 1935) is represented by Paleocene several carapaces and chelae remains. One isolated palm of Callianassidae is included. Numerous cara- Northeastern Mexico paces of Linuparus wilcoxensis Rathbun, 1935 are described, representing the most abundant lobster. A new record for the raninid Notopoides sp., and presence of Quasilaeviranina sp. cf. arzignagnensis and Quasilaeviranina ovalis are here reported. New raninids, Claudioranina latacantha sp. nov. and Claudior- anina sp. (Cyrtorhininae) are also part of this assemblage. Paraverrucoides alabamensis (Rathbun, 1935), and Tehuacana americana (Rathbun, 1935) are represented by several carapaces exhibiting intraspecific morphological variation. Different sizes among the Early and Middle Paleocene and Early Eocene decapod populations suggests a possible effect of variation in seawater temperatures and/or a Lilliput effect after the K/Pg event. © 2017 Elsevier Ltd. All rights reserved. 1. Introduction Abramovich, 2009; Smith et al., 2009; Martínez-Díaz et al., 2016). Paleocene decapod crustaceans of Northeasthern Mexico studied The Late Cretaceous/Early Paleogene (K/Pg) event has received by Vega et al. (2007) suggest important changes in the pre- and wide attention (Schulte et al., 2010; Brusatte et al., 2015). Post post K/Pg extinction faunal composition of decapod assemblages. extinction conditions and recovery periods are less well known to Similar crustacean assemblages were also reported by Rathbun date (Cope et al., 2005; Schweitzer and Feldmann, 2005; Keller and (1935) for the Paleocene (lower Selandian) Porters Creek Forma- Abramovich, 2009; Sessa et al., 2012), nor is the development of tion (previously Sucarnoochee beds) of Alabama (Mancini and Tew, strategies to confront stressful environmental post-extinction 1988) and another rich and diverse assemblage of small decapod conditions (Keller, 1989; Harries and Knorr, 2009; Keller and crustaceans from the Lower Paleocene (Danian) Mexia Clay Mem- ber, Wills Point Formation, Texas (Armstrong et al., 2009). The Rancho Nuevo Formation in the northeastern Mexican state of * Corresponding author. Coahuila offers an opportunity to compare changes in decapod E-mail address: [email protected] (F.J. Vega). http://dx.doi.org/10.1016/j.jsames.2017.01.005 0895-9811/© 2017 Elsevier Ltd. All rights reserved. 68 J.L. Martínez-Díaz et al. / Journal of South American Earth Sciences 74 (2017) 67e82 composition and the establishment of new decapod communities, 3. Systematic paleontology especially after the K/Pg event. The new material documented here is characterized by specimens of Enoploclytia gardnerae (Rathbun, Order Decapoda Latreille, 1802 1935), Linuparus wilcoxensis Rathbun, 1935, one callianassoidea, Suborder Pleocyemata Burkenroad, 1963 additional specimens of the mathildellid crab Tehuacana americana Infraorder Glypheidea Winckler, 1882 (Stenzel, 1944), and the paleoxanthopsid Paraverrucoides alaba- Superfamily Erymoidea Van Straelen, 1925 menis (Rathbun, 1935) which, show evidence of intraspecific vari- Family Erymidae Van Straelen, 1925 ation. New species of raninid crabs are also reported here and Genus Enoploclytia McCOY, 1849 compared with similar raninoids from the Lower Eocene (Ypresian) Type species: Astacus leachi Mantell, 1822, by original El Bosque Formation of Chiapas, SE Mexico. Finally, possible causes designation. are discussed for survival after the K/Pg event, successful estab- Enoploclytia gardnerae (Rathbun, 1935) lishment of new decapod communities, and persistence of some Fig. 2.A-2.C, 2.F-2.I groups. Archaeocarabus (?) gardnerae n. sp.; Rathbun, 1935, p. 75, pl. 16, 2. Geological setting Figs. 19e21. Enoploclytia gardnerae (Rathbun, 1935); Vega et al., 2007, p. Based on the occurrences of the nautiloids Cimomia haltomi 1432, Fig. 4.1e4.4. (Aldrich, 1931) and Hercoglossa sp., Murray et al. (1959) first Description.dAstacid of large size; cephalothorax triangular, documented the presence of Paleocene strata in Coahuila, north- elongated, ornamented by uniformly spaced large spines and small eastern Mexico, while Hasseltine (1968) presented details of the tubercles; deep postcervical groove, curved forward on lower stratigraphy of the sediments. McBride et al. (1974) defined a portion of carapace. Two prominent tubercles closely behind of 4000 m thick deltaic sequence of Campanian/Paleocene sediments rostrum, separated at same distance of rostrum base witdh. Strong deposited in the Parras and La Popa basins, as the Difunta Group, oblique line of spines behind cervical groove. Postcervical groove and proposed the youngest unit in eastern Parras Basin, as the with two close separated lines of strong spines curvedly aligned. Rancho Nuevo Formation. This later unit conforms an approximate Branchiocardiac groove closely to midline of carapace. All speci- 60 m sequence of sandstone, mudstone, limestone and conglom- mens are covered with strong truncated tubercles, alternating in erate. Wolleben (1977) and Vega and Perrilliat (1995) described most carapace with small spiny tubercles or punctae. Small tuber- invertebrates from the Rancho Nuevo Formation and the equivalent cles closely spaced and randomly distributed. Size of tubercles upper Potrerillos Formation (La Popa Basin). Vega et al. (1999) re- decrease in size from dorsal to ventral. Chelae much longer than ported Early Paleocene ostreid banks from the upper part of the Las carapace; subequal but of similar length, heavily ornamented with Encinas Formation, which underlies the Rancho Nuevo Formation. large, acute spines and tubercles. Merus one-fifth the total length of The K/Pg boundary was placed within the upper part of the Las cheliped; rectangular in lateral view, becomes wider at union with Encinas Formation (Murray et al., 1960; Weidie and Murray, 1967; carpus; outer surface nearly flat, covered by uniformly spaced, Hasseltine, 1968; McBride et al., 1974; Wolleben, 1977; Lawton similarly sized tubercles; inner surface flat, with small tubercles; et al., 2009; Stinnesbeck et al., 2016). The Upper Mudstone Mem- upper surface nearly flat; inner margin with evenly spaced, oblique, ber of the Potrerillos Formation in the adyacent La Popa Basin can large acute spines; outer margin with smaller spines, spaced about be correlated to the Rancho Nuevo Formation (Lawton et al., 2009); half distance as on inner marginal spines. Lower margin of merus both units include black to brownish mudstone as the main li- proximally acute, becoming wider at union with carpus, covered by thology, where invertebrates (mollusks and crustaceans) are found four large, acute spines and numerous small tubercles; distal in concretions. Klosterman et al. (2007) reported rhynchonellid margin of merus with slightly curved, deep, transverse groove, brachiopods from a Paleocene carbonate lentil of the Upper extends obliquely outward, terminates as long, large, acute spine Mudstone Member of the Potrerillos Formation, and based on that reaches proximal margin of carpus. Carpus slightly shorter 87Sr/86Sr measurements from the calcitic shells of brachiopods, the than merus, about one-seventh the total length of cheliped; sub- authors suggested an age of 57.4 Ma for the sediment containing quadrate in lateral view; outer surface concave, covered by the brachiopods. Correction to the international stratigraphic chart numerous, evenly spaced tubercles; inner surface flat, covered by (Cohen et al., 2016; updated), suggests that this age may be now small tubercles and scarce