Fernando Muñiz

A new occurence of the genus Tonkinella in northern Spain and the Middle Cambrian intercontinental correlation

The genus Tonkinella is a typical polimeroid trilobite in lower Middle Cambrian rocks from Vietnam, Canada, U.S.A., India, Korea, Siberia, China and Argentina. It has recently been found in the Mediterranean region (Iberian Chain, northeastern Spain). In this paper we refer the finding of Tonkinella aff. breviceps in the Leonian (lower Middle Cambrian) of the Cantabrian Mountains (northern Spain), analysing its stratigraphical position, fossil assemblages, biochronology and utility for intercontinental correlation. The presence of this taxon allows us to make a more accurate correlation between the Middle Cambrian biochronological scales of Laurentia, the Mediterranean area and China.

Macanopsis plataniformis nov. ichnosp. from the Lower Cretaceous and Upper Miocene of the Iberian Peninsula

Shallow sublitoral marine facies of the Lower Cretaceous in the Iberian Range (central aera, Josa, Teruel, NE Spain) and the Upper Miocene in the SW aera of the Guadalquivir Basin (Lepe-Ayamonte area, Huelva, SW Spain) have revealed the presence of the trace fossil Macanopsis plataniformis nov. ichnosp. The most characteristic feature of this ichnospecies is the presence of a subvertical shaft at the top ending in an elongated, slightly curved chamber that is subhorizontal/horizontal to the bedding plane. The new ichnospecies is interpreted as a domichnion constructed by a decapod crustacean (probably brachyuran). Cretaceous specimens are found in carbonate facies, in a shallow marine environment, low -to-moderate in energy. In Found contrast, Miocene specimens are typically in silt facies. The marine environment is confined to semi-confined, of low energy, rich in organic matter with muddy, semi-consolidated, intersively bioturbated bottom sediment.

Fossil and modern fiddler crabs (Uca tangeri: Ocypodidae) and their burrows from SW Spain: ichnologic and biogeographic implications

The burrowing activity of the only European fiddler crab species, Uca tangeri (Eydoux, 1835), was studied along the shores of the estuary of the Piedra River in Lepe, southwestern Spain. Casting of burrows allowed recognition of their simple, J-shaped to irregular architecture, which displays striking similarities to fossil Pliocene burrows in the same area. The finding of body fossils of U. tangeri in contemporaneous strata indicates these trace fossils are produced by the same species and demonstrate its presence in the eastern Atlantic coast at least for the last three million years. Burrows of U. tangeri are similar to those of other Uca spp. worldwide and also to those of other brachyurans. Their architectural simplicity makes difficult their definitive recognition in the fossil record. Nevertheless, review of existing literature confirms the presence of brachyuran burrows at least since the Cretaceous.

BIOEROSION SCARS OF ACORN BARNACLES FROM THE SOUTHWESTERN IBERIAN PENINSULA, UPPER NEOGENE

New etching trace fossils produced by the attachment of balanid barnacles on fossil molluscs, mainly bivalves, from the Upper Miocene of Cacela (southern Portugal) and Lower Pliocene of Huelva (southwestern Spain) are described. These traces are named as Anellusichnus igen. n. due to the ring-like shape of the scars. Two ichnospecies are recognized: A. circularis n. isp., consisting in a circular scar defined by a discoloured area or by a circular to subcircular trench and A. undulatus n. isp. that has a sinuous perimeter reflecting the undulate pathway of the furrow and a flat shelf etched into the substrate. Within the outer furrow both can display a cluster of circular, oval or subpolygonal concentric lines. A. undulatus n. isp. shows several morphologies that correspond to different ontogenetic stages. SHORT NOTE

Lower Pliocene Decapod crustaceans from the Southwestern Iberian Peninsula (Guadalquivir basin, Sevilla, Spain)

Abstract A new Lower Pliocene crustacean assemblage is recorded in the southwestern region of the IberianPeninsula. This assemblage is of very low diversity, being represented almost exclusively (96%) by specimens of Goneplax gulderi Bachmayer , 1953 of the family Goneplacidae. Other families represented are Callianassidae (Callianassa sp.), Laomediidae (Jaxea cf. nocturna Nardo , 1847 ) and Calappidae (Calappa cf. saheliensis Van Straelen , 1936 ) as well as Portunidae (sp. indet.). The similarity between the decapod faunas of the Mediterranean Late Miocene suggests that some Late Miocene Mediterranean decapods were also present in nearby parts of the eastern Atlantic realm, thus surviving the Messinian crisis. Initially, this western realm comprised a sublitoral environment with relatively deep quiet waters near the shore. Subsequently, the conditions became more energetic in a very shallow sublittoral setting.

New Ichnospecies of Cardioichnus from the Miocene of the Guadalquivir Basin, Huelva, Spain

A new ichnospecies of Cardioichnus, Cardioichnus reniformis isp. nov., is documented and described from marine strata of the Late Miocene of southwestern Spain. It is a bilobate resting trace with a heart‐shaped outline and is related to the work of a wedge‐shaped irregular echinoid of the spatangoid group.

Echinoderm ichnology: bioturbation, bioerosion and related processes

Abstract. Among invertebrates and both in modern and ancient marine environments, certain echinoderms have been and are some of the most active and widespread bioturbators and bioeroders. Bioturbation and/or bioerosion of regular and irregular echinoids, starfish, brittle stars, sea cucumbers and crinoids are known from modern settings, and some of the resulting traces have their counterparts in the fossil record. By contrast, surficial trails or trackways produced by other modern echinoderms, e.g., sand dollars, exhibit a lower preservation rate and have not yet been identified in the fossil record. In addition, the unique features of the echinoderm skeleton (e.g., composition, rapid growth, multi-element architecture, etc.) may promote the production of related traces produced by the reutilization of echinoderm ossicles (e.g., burrow lining), predation (e.g., borings), or parasitism (e.g., swellings or cysts). Finally, the skeletal robustness of some echinoids may promote their post mortum use as benthic islands for the settlement of hard-substrate dwellers.

Podocallichirus laepaensis, a New Ghost Shrimp (Crustacea, Decapoda, Callianassidae) from the Late Miocene of Southwest Spain

Abstract Callianassids are among the most commonly found decapod crustacean fossils but their generic assignment is often difficult. Numerous cheliped remains have been found in the upper Miocene deposits of southwest Spain allowing description of a new species of a ghost shrimp, Podocallichirus laepaensis. The assignment of the new form to the respective genus is based mainly on the morphology of the major cheliped merus and provides useful implications for paleontological studies. Podocallichirus laepaensis is the first fossil record of the genus known to date. Several specimens preserved in association with and within Ophiomorpha traces are interpreted as in situ preservation. Thus, the new ghost shrimp is identified as the producer of trace fossils.

First European record of Homiphoca (Phocidae: Monachinae: Lobodontini) and its bearing on the paleobiogeography of the genus

ABSTRACT Marine mammal fossils (except pinnipeds) have commonly been found in Pliocene marine siliciclastic layers of the Neogene Guadalquivir Basin in Southwest Spain. A few Neogene phocid innominate bones are known from the Western Paratethys and Western Atlantic. Here we describe a new innominate bone from the early Pliocene (5.3–3.6 Ma) of the Western Paratethys (Spain), which is typical of the subfamily Monachinae, and has a flattened ilium similar to representatives of the tribe Lobodontini, particularly Leptonychotes weddellii. Comparison with other fossil monachine innominates from North America, South America and South Africa reveals that this specimen represents the genus Homiphoca, but species classification remains premature. This is the first European record of the genus Homiphoca and has paleobiogeographic implications, questioning the geological age of the Varswater Formation ‘E’ Quarry, Langebaanweg, Cape Province of South Africa. This discovery from the eastern North Atlantic further implies a more regular transatlantic gene flow in Miocene and Pliocene times than today. We argue that during the Messinian-Zanclean crisis, monachines became isolated and retreated southward to lower latitudes, possibly due to climatic deterioration (during glacial stages) and competition from the cold-adapted phocines from the north. Abbreviations: NMNH: National Museum of Natural History, Smithsonian Institution, Washington, DC., USA; CMM: Calvert Marine Museum, Solomons, Maryland (USA); UTM: Universal Transverse Mercator Coordinate system