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Ammonite habitat revealed via isotopic composition and comparisons with co-occurring benthic and planktonic organisms
Journal article   Open access   Peer reviewed

Ammonite habitat revealed via isotopic composition and comparisons with co-occurring benthic and planktonic organisms

Jocelyn Anne Sessa, Ekaterina Larina, Katja Knoll, Matthew Garb, J. Kirk Cochran, Brian T. Huber, Kenneth G. MacLeod and Neil H. Landman
Proceedings of the National Academy of Sciences - PNAS, v 112(51), pp 15562-15567
22 Dec 2015
DOI: https://doi.org/10.1073/pnas.1507554112
PMID: 26630003
Featured in Collection :   UN Sustainable Development Goals @ Drexel
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https://doi.org/10.1073/pnas.1507554112View
Published, Version of Record (VoR)Maybe Open Access (Publisher Bronze),  Open

Abstract

ammonite Biological Sciences habitat reconstruction Late Maastrichtian mollusk paleoecology Physical Sciences
Because ammonites are one of the most diverse, abundant, and well-preserved clades in the history of life, they are a mainstay in macroevolutionary and biodiversity studies; however, their ecologies are poorly understood, and it is unknown whether taxa lived near the sea surface or seafloor. This uncertainty undermines their use in paleoecological and paleoenvironmental reconstructions, which depend on knowledge of organisms’ depth preferences. Here, we use a rare co-occurrence of exquisitely well-preserved ammonites and planktonic and benthic organisms to constrain depth preferences of three common ammonite families by comparing the oxygen and carbon isotopic signatures of these taxa. The ammonites fall into two distinct depth habitats, enhancing the utility of these families for highly refined paleoecological and paleoclimatic studies. Ammonites are among the best-known fossils of the Phanerozoic, yet their habitat is poorly understood. Three common ammonite families (Baculitidae, Scaphitidae, and Sphenodiscidae) co-occur with well-preserved planktonic and benthic organisms at the type locality of the upper Maastrichtian Owl Creek Formation, offering an excellent opportunity to constrain their depth habitats through isotopic comparisons among taxa. Based on sedimentary evidence and the micro- and macrofauna at this site, we infer that the 9-m-thick sequence was deposited at a paleodepth of 70–150 m. Taxa present throughout the sequence include a diverse assemblage of ammonites, bivalves, and gastropods, abundant benthic foraminifera, and rare planktonic foraminifera. No stratigraphic trends are observed in the isotopic data of any taxon, and thus all of the data from each taxon are considered as replicates. Oxygen isotope-based temperature estimates from the baculites and scaphites overlap with those of the benthos and are distinct from those of the plankton. In contrast, sphenodiscid temperature estimates span a range that includes estimates of the planktonic foraminifera and of the warmer half of the benthic values. These results suggest baculites and scaphites lived close to the seafloor, whereas sphenodiscids sometimes inhabited the upper water column and/or lived closer to shore. In fact, the rarity and poorer preservation of the sphenodiscids relative to the baculites and scaphites suggests that the sphenodiscid shells may have only reached the Owl Creek locality by drifting seaward after death.

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UN Sustainable Development Goals (SDGs)

This publication has contributed to the advancement of the following goals:

#14 Life Below Water
#13 Climate Action

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Collaboration types
Domestic collaboration
Web of Science research areas
Paleontology
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