Densely packed concentrations of sessile barnacles (Cirripedia: Sessilia) from the Early Pliocene of SE Spain

Abstract

Sessile barnacle assemblages, dominated by Concavus concavus (Bronn) and Balanus perforatus Bruguière, are very abundant in the Lower Pliocene deposits of the Almería-Níjar and Carboneras basins (southeastern Spain). They occur in shallow-coastal siliciclastic and mixed siliciclastic-carbonate sediments, forming dense concentrations in two contexts: (1) sheltered shallowmarine depressions and (2) the mouth of distributary channels feeding a delta lobe. Extensive colonization took place during periods of quiescence with a high nutrient and food supply inducing the formation of hummocks. Crowding of high morphotypes was presumably triggered by a high larval supply and recruitment rate. The barnacles are exceptionally well preserved, often as in situ clusters, many with opercula, and include a range of ontogenetic stages with some specimens preserving original colouration. Good preservation is probably due to sudden burial without further reworking.

The tropical history and future of the Mediterranean biota and the West African enigma

“…During the Early Pliocene, a regime of warm upwelling probably existed in the south-western Mediterranean, as indicated by the presence of the limpet Patella pellucida, which is associated with large seaweeds characteristic of nutrient-rich waters . High productivity, probably linked to seasonal upwelling, is also indicated for the south-western Mediterranean during the Early Pliocene by the presence of abundant aggregations of large barnacles (Aguirre et al, 2008).…”

Site selectivity of predatory borings in Late Pliocene balanid barnacles from south-east Spain

“…The specimen, RGM 791 569, housed in the Naturalis Biodiversity Center, Leiden, was collected by V.N. from the Rambla de la Sepultura in the Almeria-Nijar Basin, about 15-km east-southeast of Almeria (Aguirre & Jim enez 1997Aguirre et al 2008; fig. 1A), south-east Spain, from GPS N36.87753 W2.32770.…”

“…from the Rambla de la Sepultura in the Almeria‐Nijar Basin, about 15‐km east–south‐east of Almeria (Aguirre & Jiménez , ; Aguirre et al . ; fig. A), south‐east Spain, from GPS N36.87753 W2.32770.…”

“…Aguirre et al . () discussed the palaeoecology of barnacle concentrations in the slightly older (Lower Pliocene) deposits of the study area and noted three common species, Concavus concavus (Bronn), Balanus perforatus Bruguière and Megabalanus sp. Comparison with descriptive guides to these taxa (Buizer ; Zullo ; Southward ; Collins et al .…”

“…Aguirre et al . (, pp. 199) also listed the common bivalve shells encrusted by barnacles in these deposits, namely Ostrea edulis Linnaeus, Chlamys spp., Spondylus sp.…”