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Animal-plant relationships and paleobiogeography of an Eocene seagrass community from Florida

Linda C. Ivany, Roger W. Portell and Douglas S. Jones
Animal-plant relationships and paleobiogeography of an Eocene seagrass community from Florida
Palaios (June 1990) 5 (3): 244-258

Abstract

Fossil seagrasses are rare in the geologic record. As a result, their patterns of biogeographic distribution and community evolution are poorly understood. Though generally considered to have first appeared in the late Cretaceous, little is known of their subsequent radiation or of the timing of coevolutionary relationships between fauna and flora seen in modern communities. An excellent example of a preserved seagrass community occurs in the late Middle Eocene Avon Park Formation of west-central, peninsular Florida. This fossil assemblage provides some of the first detailed information about the evolutionary development of animal/seagrass interactions, and in addition, documents the pre-Miocene existence of seagrasses in Florida. The most common seagrasses present are species of Thalassodendron and Cymodocea. As with modern seagrass communities, a diverse assemblage of epibionts, molluscs, and echinoderms is found in association with the blades and rhizomes. Also occurring with the seagrasses and elsewhere in the formation are the remains of some of the oldest dugongs yet known. The co-occurrence of numerous juvenile ophiuroids, regular echinoids, and asteroids with the grass blades suggests that the role of the seagrass community as a "nursery" had already been established by the Eocene. This role of providing food and protection for the young of many organisms is well-documented in the modern realm, but has never before been reported from the fossil record. A strong Tethyan paleobiogeographic connection, previously noted among the Eocene molluscs of Florida, is also supported by the seagrasses and dugongs. We hypothesize that this assemblage of seagrasses was much more widespread in the Neotropics during the Paleogene and into the Neogene. Their absence now can be explained by the changing circulation patterns and cooling initiated by the closing of the Panamanian Isthmus and/or the onset of Plio-Pleistocene glaciation.


ISSN: 0883-1351
Serial Title: Palaios
Serial Volume: 5
Serial Issue: 3
Title: Animal-plant relationships and paleobiogeography of an Eocene seagrass community from Florida
Affiliation: Fla. Mus. Nat. Hist., Gainesville, FL, United States
Pages: 244-258
Published: 199006
Text Language: English
Publisher: Society of Economic Paleontologists and Mineralogists, Tulsa, OK, United States
References: 68
Accession Number: 1991-019209
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Univ. Fla., Contrib. Paleobiol., No. 359
N27°00'00" - N29°00'00", W82°49'60" - W80°04'60"
N28°38'60" - N29°01'60", W82°43'60" - W82°10'60"
N29°00'00" - N29°34'60", W83°13'00" - W82°25'00"
Secondary Affiliation: Univ. Fla., USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 1991
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