Environmental control and dynamics of Lower Jurassic bivalve build-ups in the Trento Platform (Southern Alps, Italy)

The oyster enigma variations: a hypothesis of microbial calcification

“…Modern photosymbiotic bivalves are not cemented to the substrate and have a compact shell microstructure, but there is no fundamental incompatibility between a porous shell structure and the presence of photosymbionts. In fact, these conditions might well complement one another in large bivalves living in well-lit yet relatively productive waters, environments suggested for many rudists and lithiotids (Gili et al 1995;Posenato and Masetti 2012;Vermeij 2013). Richthofeniacean brachiopods, which likely were photosymbiotic (Cowen 1970(Cowen , 1983, also combined this habit with the oyster syndrome.…”

Megaspores from the Lower Jurassic (Pliensbachian) Rotzo Formation (Monti Lessini, northern Italy) and their palaeoenvironmental implications

“…The studied clayey layer is 10-15 cm thick and sits on top of a 80-cm-thick Lithiotis bank (Fig. 2), along the stream near the pathway to Vajo dell'Anguilla close to the section studied by Clari (1975) and Posenato and Masetti (2012). The samples (about 2 kg of loose sediment) from the Vajo dell'Anguilla outcrop come from an organic-rich horizon called VA1 containing Lithiotis, solitary corals, ostracods, coal fragments and amber.…”

“…The westernmost sector (Monte Baldo and Adige River area) is mainly characterised by marginal oolitic shoals. The typical facies of the Rotzo Formation are ooidal, peloidal, bioclastic and intraclastic limestones with marly and clayey horizons rich in plant remains and thin coal levels (Broglio Loriga and Neri 1976;Boomer et al 2001;Roghi and Romano 2008;Posenato and Masetti 2012). Macrofossils are common and include molluscs (large and small bivalves such as Lithiotis s.l.…”

“…Recently, Neri et al (2016) described the first amber from this formation. The Rotzo Formation has been dated, based on foraminifera, ammonites, green algae and isotopic analyses ( 13 C and 87 Sr/ 86 Sr), to the Pliensbachian (Avanzini et al 2006;Fugagnoli 2004;Posenato and Masetti 2012;Franceschi et al 2014). …”

Revisión De Los Biocoremas Marinos Globales Del Jurásico Según La Distribución De Los Moluscos Bivalvos

“…Tanto el contexto geológico, como la geometría y la estructura interna de esos cuerpos arrecifales de Lithiotis fueron comparados con las calizas cretácicas con rudistas. Los arrecifes alpinos alcanzaron hasta 5 m de espesor y decenas de metros de longitud, y los bivalvos que los construyeron exhibían un amplio rango de adaptaciones, incluyendo conchillas muy espesas con valvas muy desiguales, una de ellas actuando como un fino opérculo elástico, crecimiento alométrico de las porciones apicales, y una notable variabilidad fenotípica (véase discusión en Chinzei, 1982;Savazzi, 1996;Posenato y Masetti, 2012). Se propuso incluso la posibilidad de simbiosis con algas verdes (AccorsiBenini y Broglio-Loriga, 1977;Fraser et al, 2004), lo que fue luego desafiado sobre la base del análisis de los incrementos de crecimiento (Accorsi-Benini, 1985), atribuyéndose el gran tamaño de la conchilla a un crecimiento a tasas normales durante una muy larga vida (hasta 30 años).…”