ELASMOBRANCHIAN REMAINS FROM THE LOWER BARREMIAN ...

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ELASMOBRANCHIAN REMAINS FROM THE LOWER BARREMIAN OF NORTH-. EASTERN SPAIN (PROVINCE OF TERUEL): PRELIMINARY REPORT.
ELASMOBRANCHIAN REMAINS FROM THE LOWER BARREMIAN OF NORTHEASTERN SPAIN (PROVINCE OF TERUEL): PRELIMINARY REPORT JÜRGEN KRIWET Institut für Paläontologie, Freie Universität Berlin, Malteserstraße 74-100, Haus D, 12249 Berlin, Germany

INTRODUCTION ln this paper, two selachian faunas from north-eastern Spain are described. Although the selachian remains do not come from Iithographie Iimestones but from clastic sediments in the northern parts of the Province of Teruel, they are an important contribution to the knowledge of Lower Cretaceous elasmobranchs from Spain. ln addition, it is possible to make some considerations in respect to the ecology of the sharks from the Iithographie; Iimestones of the Sierra of Montsech, Province of Lerida. Systematic excavations, carried out by members of the Institute for Paleontology of the Free University of Berlin (IPFUB) in the 1960s yielded an abundant selachian fauna from two closely situated localities. Both were dated as Lower Barremian based on charophytes (ScHUDACK 1989, pers. comm. 1994).

THE LOCALITY ALCAINE The Stratigraphie column near the small village of Alcaine consists of alternating micritic Iimestones and greyish marls. At the basis of the outcrop, greenish to red claybeds with an oscillating content of sand are exposed. These clays are known as «arcillas rojas». Several samples from the «arcillas rojas» were washed and concentrated by using the «Henkel process» and the floral and faunal contents were picked out under a stereomicroscope. Apart of invertebrates and other «lower» vertebrales, nearly 500 selachian remains of fifteen species are represented (Tab. 1).

Tab. 1. Composition of the floral and faunal assemblage of Alcaine Flora wood remains charophytes lnvertebrates solitary corals gastropedes pelecypodes belemnites ostracodes Crustacea indet. bryozoans regular echinoderms Actinopteryglans Coelodus sp. Pycnodontidae indet. Caturus sp. ?Lepidotes sp. alepisauroid-like fisches teleostean vertebrae

Etasmobranchs Hybodus sp. Lissodus microselachos {ESTES &SANCH(Z, 1982) Polyacrodus sp. Heterodontus canaliculatus {EGERTON, 1850) Hemiscyllium n. sp. Cretoxyrhinidae n. gen. et n. sp. Scyliorhinidae n. gen. et n. sp. Protoscyliorhinus lamaudi BI DOLE & LANDEMAIN, 1989 Rhinobatos picteti CAPPETTA, 1975 Rhinobatos sp. Sclerohynchidae n. gen. et n. sp. Sechmetia n. sp. Pseudohypolophus mcnultyi (THURMOND, 1971) Protoplatyrhina sp. cf. renae CASE, 1978 Reptilia Crocodilia indet

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The abundance of hybodonts, especially Lissodus microselachos (EsTES & SANCHiz 1982) is striking. Hybodont remains are often thought to be typical and indicativ for brackish or even fresh waters in the Lower Cretaceous, but no detailed investigation has been carried out so far to prove this. ln contrast, the occurence of hybodonts, as documented in the literature, favors a primary brackish or even marine mode of living. Only a few highly specialized forms obviously entered streams and even lakes. Further investigations into the sedimentology of hybodont localities are necessary to settle this problem. No mesopelagic or bathyal neoselachians (e.g. Squaliformes) are present. Only one genus can be cautiously refered to the Cretoxyrhinidae due to similarities to Leptastyrax and Protolamna. The Cretoxyrhinidae were the most voracious of all fish predators in the Cretaceous seas (WELTON & FARISH 1993). They surely occupied an ecological niche equivalent tothat filled by large mackerel sharks in recent seas. Therefore they certainly were coastal, as weil as oceanic sharks of the epipelagic zone. The remaining eleven species were sluggish bottom dwellers (like the batoids) or animals that lived close to the bottom. Extant rhinobatoids are rarely found below 200 m, and some species even invade fresh waters. However, the invasion of fresh water by several groups presumably took place chiefly in postcretaceous times. Sharks (Heterodontus, Hemiscyl/ium, Scyliorhinidae) are represented by small benthic forms, which usually live in shallow epicontinental seas. All neoselachian taxa indicate tropical to warm temperate conditions. The information given by floral and faunal aspects can be summarized as follows: The sediments of Alcaine were laid down in a shallow epicontinental sea not deeper than 150 to 250 meters. The sandy components, as weil as the charophytes and some ostracodes indicate a minor terrestrial influence.

THE LOCALITY GALVE Here, a diverse tetrapod fauna was recovered from Wealden deposits. For a complete faunal Iist see BuscAUONI & SANZ (1987) and KREBS (1993). The small fish fauna was revised by EsTES & SANCHiz (1982). Apart from actinopterygians, two hybodonts were described in this paper. Since then, no further investigations were carried out. Nearly 50 elasmobranch teeth were found in the collection of the IPFUB. A reevaluation of the material described by EsTES & SANCHiz (1982) was not possible. The Hybodus parvidens described by them might be a Polyacrodus. The other hybodont, Lissodus microselachos (EsTEs & SANCHiz), which is present in this locality is also represented by over 150 teeth from Alcaine. ln addition, another indeterminable species of Lissodus and two of Polyacrodus are found in the Berlin material from Galve. A dozen teeth are very similar to Egertonodus basanus with respect to crown morphology, but the separation of Hybodus and Egertonodus on the basis of tooth morphology remains questionable. Only two neoselachian sharks can be reported: One tooth of Cretolamna appendiculata (the oldest known record of this species), and five teeth of the cretoxyrhinid, which is also found in Alcaine. The associated fish fauna comprises teeth of Coe/odus, Caturus, ? Lepidotes, Pycnodontidae indet. and other bony fishes . Although the deposits of Galve are usually interpreted as exclusively terrestrial sediments, the composition of the selachian and actinopterygian association suggests several marine ingressions in the Wealden.

THE LOCALITY MONTSECH: From the Lower Cretaceous Iimestones of the Sierra del Montsech, vertebrale fossils have been known for a lang time. Despite all arguments for these deposits to represent Iake sediments, which were laid down under calm conditions, the actinopterygian fauna is very similar to that of the Solnhofen Iimestones in several aspects, but no neoselachians have been found so far. Hybodonts are represented by species of Hybodus and Lissodus, which are now under detailled study by F.J. Poyato-Arriza and R. Solar-Gij6n. As already mentioned, these taxa are not necessarily primary inhabitants of a Iake, but might have invaded this environment during marine ingressions.

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ACKNOWLEDGEM ENTS:

I would like to thank Prof. Dr. B. KREBS (Berlin) for providing the specimens from Alcaine and Galve and for reviewing the manuscript.

LITERATURE

BuscALIONI, A.D. & SANZ, J.L. {1987): Lista faunistica de los vertebrados de Galve (Teruel). - Estudios geol., vol. extr. Galve-Tremp, 1987: 66-67. Esres, R. & SANCHiz, B. {1982): Early Cretaceous lower vertebrales from Galve (Teruel), Spain. - J. Vert. Paleont., 21(1): 21-39, 12 Abb., 2 Tab. KREBS, B. (1993): Das Gebiß von Crusafontia (Eupantotheria, Mammalia)- Funde aus der UnterKreide von Galve und Ufia (Spanien). - Berliner geowiss. Abh. (E), 9: 233-252, 7 Abb. WELTON, B.J. & FARISH, R.F. (1993): The collector's guide to fossil sharks and rays from the Cretaceous of Texas. - XVIII+204 pp.; Lewisville (Betore Time).

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