Dissecting "Lithiotis" Bivalves: Implications for the Early Jurassic Reef Eclipse

Other| February 01, 2004 Dissecting "Lithiotis" Bivalves: Implications for the Early Jurassic Reef Eclipse NICOLE M. FRASER; NICOLE M. FRASER 1Department of Earth Sciences, University of Southern California, Los Angeles, CA, 90089-0740, N.Fraser@nhm.ac.uk *Current address: Department of Palaeontology, The Natural History Museum, Cromwell Road, London, SW7 5BD, UK. Search for other works by this author on: GSW Google Scholar DAVID J. BOTTJER; DAVID J. BOTTJER 1Department of Earth Sciences, University of Southern California, Los Angeles, CA, 90089-0740, N.Fraser@nhm.ac.uk Search for other works by this author on: GSW Google Scholar ALFRED G. FISCHER ALFRED G. FISCHER 1Department of Earth Sciences, University of Southern California, Los Angeles, CA, 90089-0740, N.Fraser@nhm.ac.uk Search for other works by this author on: GSW Google Scholar Author and Article Information NICOLE M. FRASER *Current address: Department of Palaeontology, The Natural History Museum, Cromwell Road, London, SW7 5BD, UK. 1Department of Earth Sciences, University of Southern California, Los Angeles, CA, 90089-0740, N.Fraser@nhm.ac.uk DAVID J. BOTTJER 1Department of Earth Sciences, University of Southern California, Los Angeles, CA, 90089-0740, N.Fraser@nhm.ac.uk ALFRED G. FISCHER 1Department of Earth Sciences, University of Southern California, Los Angeles, CA, 90089-0740, N.Fraser@nhm.ac.uk Publisher: SEPM Society for Sedimentary Geology Accepted: 10 Oct 2003 First Online: 03 Mar 2017 Online ISSN: 1938-5323 Print ISSN: 0883-1351 Society for Sedimentary Geology PALAIOS (2004) 19 (1): 51–67. https://doi.org/10.1669/0883-1351(2004)019<0051:DLBIFT>2.0.CO;2 Article history Accepted: 10 Oct 2003 First Online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation NICOLE M. FRASER, DAVID J. BOTTJER, ALFRED G. FISCHER; Dissecting "Lithiotis" Bivalves: Implications for the Early Jurassic Reef Eclipse. PALAIOS 2004;; 19 (1): 51–67. doi: https://doi.org/10.1669/0883-1351(2004)019<0051:DLBIFT>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyPALAIOS Search Advanced Search Abstract Following extensive Late Triassic coral-constructed reefs and the aftermath of the Triassic–Jurassic mass extinction, Early Jurassic buildups are rare and constructed primarily by bivalves. The Pliensbachian exhibits a radiation of aberrant pterioid bivalves, the "Lithiotis" bivalves, which include: Lithiotis problematica, Cochlearites loppianus, Gervilleioperna sp., Mytiloperna sp., and Lithioperna scutata. These large bivalves are ubiquitous in shallow, nearshore tropical waters and restricted to the Early Jurassic recovery interval. Field and thin-section observations indicate a strong zonation of "Lithiotis" bivalves in shallow nearshore environments. Gervilleioperna and Mytiloperna are restricted to tidal-flat and inner-platform facies. Lithioperna scutata is found throughout the lagoonal subtidal facies and even in some low-oxygen environments. Lithiotis and Cochlearites construct buildups in subtidal facies, and both taxa exhibit discordant valves—one valve is converted into a pedestal, the other is an opercular valve. The largest buildups attain lengths over 60 m and thicknesses of 3–5 m. It is proposed that the reef-building bivalves Lithiotis problematica and Cochlearites loppianus filled the relatively empty ecological niche of reef-building during the Early Jurassic (Lias), only to be replaced by their predecessors, the scleractinian corals, by the Middle Jurassic. The other "Lithiotis" bivalves (Lithioperna scutata, Mytiloperna, and Gervilleioperna sp.) lived in restricted lagoonal environments with possible fluctuating salinity on Early Jurassic (Liassic) carbonate shelves. Lithiotis and Cochlearites, in contrast to many oysters, do not orient their commissure planes in a single direction. Instead, these two buildup-constructing genera radiate out from a central bouquet, possibly maximizing exposure to light rather than current. Due to their growth habit, extensive calcification, presumed oligotrophic environment, and pseudocoloniality, these two genera may have harbored photosymbionts. Severe environmental changes and associated unusual seawater chemistry of the protracted Early Jurassic recovery may have led to suppressed coral-reef growth and the rapid radiation of reef-building bivalves. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.