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A new marine vertebrate assemblage from the Late Neogene Purisima Formation in Central California, part II: Pinnipeds and Cetaceans Robert W. BOESSENECKER Department of Geology, University of Otago, 360 Leith Walk, P.O. Box 56, Dunedin, 9054 (New Zealand) and Department of Earth Sciences, Montana State University 200 Traphagen Hall, Bozeman, MT, 59715 (USA) and University of California Museum of Paleontology 1101 Valley Life Sciences Building, Berkeley, CA, 94720 (USA) [email protected] Boessenecker R. W. 2013. — A new marine vertebrate assemblage from the Late Neogene Purisima Formation in Central California, part II: Pinnipeds and Cetaceans. Geodiversitas 35 (4): 815-940. http://dx.doi.org/g2013n4a5 ABSTRACT e newly discovered Upper Miocene to Upper Pliocene San Gregorio assem- blage of the Purisima Formation in Central California has yielded a diverse collection of 34 marine vertebrate taxa, including eight sharks, two bony fish, three marine birds (described in a previous study), and 21 marine mammals. Pinnipeds include the walrus Dusignathus sp., cf. D. seftoni, the fur seal Cal- lorhinus sp., cf. C. gilmorei, and indeterminate otariid bones. Baleen whales include dwarf mysticetes (Herpetocetus bramblei Whitmore & Barnes, 2008, Herpetocetus sp.), two right whales (cf. Eubalaena sp. 1, cf. Eubalaena sp. 2), at least three balaenopterids (“Balaenoptera” cortesi “var.” portisi Sacco, 1890, cf. Balaenoptera, Balaenopteridae gen. et sp. indet.) and a new species of rorqual (Balaenoptera bertae n. sp.) that exhibits a number of derived features that place it within the genus Balaenoptera. is new species of Balaenoptera is relatively small (estimated 61 cm bizygomatic width) and exhibits a comparatively nar- row vertex, an obliquely (but precipitously) sloping frontal adjacent to vertex, anteriorly directed and short zygomatic processes, and squamosal creases. Fossil odontocetes include the lipotid “river dolphin” Parapontoporia sternbergi (Greg- ory & Kellogg, 1927), four true porpoises including a bizarre new genus also known from other strata (Phocoenidae indet., Phocoenidae unnamed genera 1 and 2, and cf. Phocoena), an indeterminate delphinid (Delphinidae indet.) a pilot whale-like delphinid (cf. Globicephalinae indet.), an undetermined sperm whale (cf. Physeteroidea indet.), and an indeterminate odontocete. e new record of Parapontoporia sternbergi is noteworthy as it represents the first association of any earbones (petrosal, tympanic bulla, malleus, and incus) for the extinct genus. Discovery and description of a complete marine mammal assemblage permits faunal comparisons with other published Pliocene marine mammal assemblages from around the globe. e aggregate Pliocene marine mammal assemblage from GEODIVERSITAS • 2013 • 35 (4) © Publications Scientifiques du Muséum national d’Histoire naturelle, Paris. www.geodiversitas.com 815 Boessenecker R. W. eastern North Pacific (ENP) shares little in common with the modern fauna, and is mostly composed of extinct genera; notably, phocoenids and odobenids were more diverse than in the ENP today. is indicates that the modern fauna KEY WORDS of the ENP did not emerge until after the end of the Pliocene, and probably Marine mammals, sometime during the Early Pleistocene. e Pliocene ENP assemblage is similar Pinnipedia, to that of Japan, and the North Pacific in general shares little with south Pacific, Mysticeti, Odontoceti, Mediterranean, or North Atlantic marine mammal assemblages, indicating the Pliocene, North Pacific hosted a provincial marine mammal fauna that evolved in isola- Pleistocene, Purisima Formation, tion from the modern marine mammal fauna, which had already appeared in new species. the North Atlantic by the Early Pliocene. RÉSUMÉ Un nouvel assemblage de vertébrés marins de la Formation Purisima, Californie centrale, partie II : les Pinnipèdes et les Cétacés. La nouvelle faune découverte à San Gregorio (Miocène supérieur à Pliocène supé- rieur) dans la Formation Purisima en Californie Centrale a permis de constituer une collection de 34 taxons de vertébrés, dont huit espèces de requins, deux de poissons osseux, trois d’oiseaux marins (décrits dans une étude antérieure) et 21 de mammifères. Les pinnipèdes comprennent un morse Dusignathus sp., cf. D. seftoni, un otarie à fourrure Callorhinus sp., cf. C. gilmorei et des os indéterminés d’otaries. Les baleines comprennent des mysticètes nains (Herpetocetus bramblei Whitmore & Barnes, 2008, Herpetocetus sp.), deux baleines franches (cf. Eubalaena sp. 1, cf. Euba- laena sp. 2), au moins trois balénoptères (“Balaenoptera” cortesi “var.” portisi Sacco, 1890, cf. Balaenoptera, Balaenopteridae gen. et sp. indet.) et une nouvelle espèce de rorqual (Balaenoptera bertae n. sp.) qui présente des caractères dérivés permettant de la placer au sein du genre Balaenoptera. Cette nouvelle espèce de Balaenoptera est relativement petite (largeur bizygomatique estimée à 61 cm) et montre un vertex relativement étroit, un frontal avec une pente forte, une apophyse zygo- matique courte et dirigée antérieurement, et un squamosal plissé. Les odontocètes fossiles comprennent un Lipotidae (dauphin de rivière) Parapontoporia sternbergi (Gregory & Kellogg, 1927), quatre vrais marsoins incluant un étrange nouveau genre connu dans d’autres niveaux (Phocoenidae indet., Phocoenidae genres non nommés 1 et 2, et cf. Phocoena), un dauphin indéterminé (Delphinidae indet.), un globicéphale (cf. Globicephalinae indet.), un cachalot indéterminé (cf. Physeteroi- dea indet.) et un odontocète indéterminé. La nouvelle signalisation de Paraponto- poria sternbergi est remarquable car elle représente la première association d’os de l’oreille (petrosal, bulle tympanique et incus) pour ce genre fossile. La découverte et la description d’un assemblage complet de mammifères marins autorise une comparaison avec d’autres assemblages de mammifères marins pliocènes dans le monde. L’assemblage de mammifères marins du Pliocène de l’Est du Nord Pacifique (ENP), présente peu de similitudes avec la faune moderne et est principalement composé de genres éteints, particulièrement des phocoenidés et des odobenidés qui étaient plus diversifiés que dans l’ENP actuel. Ceci indique que la faune moderne MOTS CLÉS de l’ENP n’émerge pas après la fin du Pliocène mais probablement à un moment Mammifères marins, du Pléistocène ancien. L’assemblage ENP pliocène est semblable à celui du Japon Pinnipedia, et du Nord du Pacifique en général présente peu de point communs avec ceux du Mysticeti, Odontoceti, Sud du Pacifique, de Méditerranée ou du Nord de l’Atlantique. Ceci indique que Pliocène, la faune marine de mammifère pliocène du Nord du Pacifique était marquée d’un Pléistocène, Formation Purisima, provincialisme et a évolué de manière isolée de la faune moderne, qui était déjà espèce nouvelle. apparue dans le Nord de l’Atlantique au Pliocène inférieur. 816 GEODIVERSITAS • 2013 • 35 (4) Marine mammals from Purisima Formation, California INTRODUCTION as a particular new marine mammal taxon. ere are few assemblages for which the majority of e fossil record of the west coast of the United marine vertebrate taxa have been documented. States and Mexico has long been known to yield In contrast to the well-published fossil record of rich assemblages of marine vertebrates of Cenozoic Neogene pinnipeds, desmostylians, and sirenians, age (Jordan & Hannibal 1923; Kellogg 1927, 1931; there are comparatively few publications which are Barnes 1977; Repenning & Tedford 1977; Domning concerned with accompanying sharks, bony fish, 1978; Warheit 1992; Miyazaki et al. 1995; Barnes birds, and cetaceans (Late Miocene cetaceans in 1998; Deméré et al. 2003). Many of the earliest particular; Barnes 1977), despite being numeri- discovered fossil vertebrates from this region are cally abundant in museum collections. e 2004 marine mammals from Miocene and Pliocene discovery of a new marine vertebrate assemblage strata, and include enigmatic odontocetes such as in the Upper Miocene-Upper Pliocene Purisima Lonchodelphis occiduus Leidy, 1858 and Hesperocetus Formation (Boessenecker 2006, 2011a) yielded californicus True, 1912, early records of fossil pin- enough fossils to permit study and description of an nipeds (Pontolis magnus True, 1903, Desmatophoca entire marine vertebrate assemblage. Previously, the oregonensis Condon, 1906 and Allodesmus kernensis fossil sharks, birds, and bony fish were described in Kellogg, 1922), and the desmostylian Desmostylus detail by Boessenecker (2011a) and Boessenecker & hesperus Marsh, 1888. Subsequent discoveries in Smith (2011). e purpose of this study is to de- this region during the middle and late twentieth scribe the remainder of the assemblage, compris- centuries have resulted in a series of major advances ing 21 pinniped, odontocete, and mysticete taxa. in the study of marine mammal evolution and Description of this assemblage permits comparison paleontology, including the discovery of the oldest with the similarly aged San Diego Formation of pinnipeds (Oligo-Miocene; Mitchell & Tedford southern California, consideration of the aggregate 1973; Barnes 1979; Berta et al. 1989), the earliest Pliocene marine mammal assemblage from the informative discoveries of toothed mysticetes (Late eastern North Pacific in general, and comparison Oligocene; Emlong 1966; Barnes et al. 1995), ar- with other published marine mammal assemblages chaic desmostylian fossils which alleviated a host of from across the globe. issues concerning their phylogenetic origins (Late Oligocene; Domning