Boletín de la Sociedad Geológica Mexicana ISSN: 1405-3322 Sociedad Geológica Mexicana, A.C. Ifrim, Christina Schlueterella stinnesbecki n. sp. (Ammonoidea, Diplomoceratidae) from the Turonian-Coniacian of northeastern Mexico Boletín de la Sociedad Geológica Mexicana, vol. 71, no. 3, 2019, September-December, pp. 841-849 Sociedad Geológica Mexicana, A.C. DOI: https://doi.org/10.18268/BSGM2019v71n3a13 Available in: https://www.redalyc.org/articulo.oa?id=94366148013 How to cite Complete issue Scientific Information System Redalyc More information about this article Network of Scientific Journals from Latin America and the Caribbean, Spain and Journal's webpage in redalyc.org Portugal Project academic non-profit, developed under the open access initiative Boletín de la Sociedad Geológica Mexicana / 2019 / 841 Short note Schlueterella stinnesbecki n. sp. (Ammonoidea, Diplomoceratidae) from the Turonian–Coniacian of northeastern Mexico Christina Ifrim ABSTRACT Christina Ifrim ABSTRACT RESUMEN [email protected] Institut für Geowissenschaften, Universität Heidelberg, Im Neuenheimer Feld 234, 69120 A new species of the genus Schlueterella Se describe una nueva especie del género Heidelberg, Germany. Wiedmann, 1962 is here described. Schlueterella Wiedmann, 1962. Los veinte Twenty specimens of this hetero- ejemplares de este ammonoideo heteromorfo morph ammonoid were collected fueron colectados en el norte de Coahuila, in northern Coahuila, Mexico. México. Parece que Schlueterella stinnes- Schlueterella stinnesbecki n. sp. seems to becki n. sp. fue una especie endémica en el have been an endemic form in the Turoniano tardío–Coniaciano temprano. late Turonian–early Coniacian. This Con total certeza se trata del registro más is the oldest definite record of the antiguo de este género y una forma básica genus and a basal form in its evolu- en su evolución desde Neocrioceras. tion away from Neocrioceras. Keywords: Ammonoid, Cretaceous, Palabras clave: Ammonoideo, Turonian, Coniacian, Mexico, Cretácico, Turoniano, Coniaciano, endemic. México, endémico. n. sp. from Mexico BOL. SOC. GEOL. MEX. 2019 VOL. 71 NO. 3 P. 841 ‒ 849 http://dx.doi.org/10.18268/BSGM2019v71n3a13 Manuscript received: April 6, 2018. Corrected manuscript received: July 1, 2018. Manuscript accepted: July 10, 2018. Schlueterella stinnesbecki 8422 / Boletín de la Sociedad Geológica Mexicana / 2019 1. Introduction coil, tubercles from simple or double ribs always on the primaries, if not all ribs bear tubercles. Schlueterella Wiedmann, 1962 is a little known Originally, Schlueterella was introduced as subgenus genus, the affinities of which are still debatable. of Neocrioceras by Wiedmann (1962). The type INTRODUCTION / SYSTEMATIC PALEONTOLOGY The specimens described here were discovered species of Neocrioceras is Crioceras spinigerum Jimbo, in northeastern Mexico in the years 2002–2006 1894, (pl. 8, figure 1) sensu Diener, 1925, (p. 192). and 2018. They originated from two quarries in Neocrioceras was erected by Spath (1921) on the the quarry area of the municipality of Múzquiz, basis of a juvenile whorl of Crioceras spinigerum northwest Coahuila. The Rosario section (R, Jimbo, 1894 (= Schlueterella compressa sensu Klinger, 28°52.586ʹN, 102°24.222ʹW, Figure 1) comprises 1976). An emended description of this species the Turonian–Coniacian boundary from the Myti- was given by Diener (1925). In Neocrioceras, juve- loides scupini Zone to the upper Cremnoceramus crassus nile whorls are moderately helicoid, later more or inconstans Zone (Stinnesbeck et al., 2005; Ifrim et less crioconic with circular to depressed section, al., 2014), whereas the Carranza section (CA, dense straight to prorsiradiate ribs, some with 29°10.775ʹN, 102°27.193ʹW, Figure 1) is much lateral tubercles and ventrolateral tubercles or shorter and comprises only the middle part of the nodes, the latter opposite or alternating on venter. lower Coniacian Cremnoceramus crassus inconstans According to Wiedmann (1962), Schlueterella differs Zone (Ifrim et al., 2011). In both quarries, Schluet- from Neocrioceras in having corresponding instead erella stinnesbecki n. sp. is a common species. of alternating ribs and in having more complex instead of simple ribbing. 2. Systematic Paleontology 102°W 101°W 100°W Higher systematics follows Wright et al. (1996) except for the subfamily and genus for reasons SCNP CARRANZA discussed below. Terminology for tubercles, nodes, 29°N ROSARIO Piedras and spines follows Ifrim et al. (2018). Negras Repository is the Paleontological Collection (Colección de Paleontología, CPC), housed in the Desert Museum (Museo del Desierto), Saltillo, 28°N Coahuila. For lithostratigraphy see Stinnesbeck et Laredo al. (2005). For the Rosario section see Ifrim et al. (2014). For the Carranza section and its correla- N tion see Nyborg et al. (2014) and Ifrim et al. (2011). Monclova 27°N Further abbreviations are D: diameter, WH: whorl Cuatro Cienegas Vallecillo height, WI: Distance between whorl at D and pre- 50 km vious whorl, U: umbilicus. Suborder Ancyloceratina Wiedmann, 1966 n. sp. from Mexico Superfamily Turrilitoidea Gill, 1871 Rosario Family Diplomoceratidae Spath, 1926 Subfamily Diplomoceratinae Spath, 1926 Genus Schlueterella Wiedmann, 1962 Linares Type species. Ancyloceras pseudoarmatum Schlüter, Figure 1 Map of Mexico with the state of Coahuila in gray (below), 1872 by original designation of Wiedmann (1962, and zoom on northern Coahuila with location of the Rosario and p. 205). The genus is characterized by an open Carranza quarries (above). Schlueterella stinnesbecki Boletín de la Sociedad Geológica Mexicana / 2019 / 8433 Wright et al. (1996) placed the subgenus Schlueterella of 0.25 to 0.30 (Figure 4). Irregular coiling causes under the genus Pseudoxybeloceras, a view rejected variation in WI/D between 0.09 and 0.21 in juve- here based on the overall morphology of more nile whorl and decreases to 0.06 to 0.16 at D > complete specimens that show a coiling pattern 90 mm. U/D decreases slightly from 0.58–0.73 at that matches Neocrioceras, and because Schlueterella small D to 0.53–0.63 at D > 90 mm. SYSTEMATIC PALEONTOLOGY is interpreted here to have evolved from Neocrioc- Ornament consists of up to 38 primary ribs per eras. It may be justified to place some fragmented whorl which are straight to prorsiradiate near the specimens with straight shafts in the genus dorsum and flex back umbilicolaterally in a wide Pseudoxybeloceras. arch to become rursiradiate towards the venter. The specimens described here match the original They wear tubercles on midflank and ventrolateral definition of Schlueterella of Wiedmann (1962). In nodes or spines. Primary ribs are closer in the juve- addition, they have a crioconic shell, but with small nile stage, and one to two simple secondaries are portions of straighter coiling, but lacking straight intercalated. This number increases to 2–4 simple shafts as in the Polyptochoceratinae. Matsumoto and secondaries at D between 50 and 100 mm, their Miyauchi (1984) raised Schlueterella to genus level, number increasing with growth. They parallel the a view followed by Klinger et al. (2007) and Sum- primaries. Suture not preserved. mesberger et al. (2017), among others. This genus Types. The holotype is CPC–990 (Figure 3.5, is further interpreted here to have evolved from also figured in Stinnesbeck et al., 2005, Figure Neocrioceras and thus included into the subfamily 8f) from an unknown bed in the Yellow Member Diplomoceratinae. of the Rosario quarry. Paratypes are CPC–853, CPC–914 to –927 and CPC–989 from the from Schlueterella stinnesbecki n. sp. the uppermost Turonian (Cremnoceramus walters- Figure 2.1–2.12, Figure 3.1–3.5, Figure 4 dorfensis W. Zone) to lower Coniacian (C. crassus inconstans Zone), i.e., the upper Gray Member and 2005 ? Neocrioceras sp.; Stinnesbeck et al., fig. 8f the Yellow Member of the Rosario quarry, and the 2007 ? Neocrioceras sp.; Ifrim et al., fig. 6d Yellow Member in the Carranza quarry. Diagnosis. Crioconic, in the juvenile stage mod- Dimensions. See Table 1. erately helicoid shell with up to 38 rursiradiate, Occurrence. Schlueterella stinnesbecki sp. nov. is only simple primary ribs per whorl bearing lateral known from northwest Coahuila. It was recorded tubercles and ventrolateral nodes or spines with- from the uppermost Turonian (waltersdorfensis out looping, intercalated regularly by one simple, Zone) to lower Coniacian (inconstans Zone), beds parallel secondary rib in the juvenile stage and to R24–R42 of the Gray and Yellow members of four in the adult stage. The transition from juve- the Rosario quarry and beds CA1 to CA6 of the nile to adult ornament is either at D around 50 or Carranza quarry (compare Ifrim et al., 2011, with around 100 mm, indicative of size dimorphism. Ifrim et al., 2014 for correlation). Etymology. This species is named in honor of Discussion. Wiedmann (1962) differentiated Wolfgang Stinnesbeck for his extensive paleonto- two groups within Schlueterella. The group around logical work in Latin America since 1990, includ- Sch. pseudoarmatum (Schlüter, 1872) bears four rows n. sp. from Mexico ing a series of pioneer projects in northeastern of tubercles on primary double ribs, whereas the Mexico. group around Sch. kossmati (Simionescu, 1899) Description. Juvenile shell is crioconic to mod- bears tubercles on simple primaries, or all ribs bear erately helicoid and slightly irregular (Figure 2), tubercles. The specimens described here clearly adult crioconic (e.g., Figure 3.5). Juvenile