Ichthyoliths as paleoceanographic and paleoecological proxy and the response of open-ocean fish to Cretaceous and Cenozoic global change

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Author(s): Sibert, Elizabeth Claire
Source: 233p. Institution: University of California at San Diego, La Jolla, CA, United States
Note: In English. 259 refs. Doctoral dissertation
Summary: Ichthyoliths, isolated fossil fish teeth and shark dermal scales preserved in deep-sea sediment cores, can reveal how marine vertebrate consumers (sharks and fish) have responded to major global change events in Earth's history. In this dissertation, I first develop methods for the isolation and curation of ichthyoliths from a variety of marine sediment types. I then use ichthyoliths to assess how (1) total fish production, (2) pelagic fish community structure, and (3) fish evolution have responded to select global change events in Earth's history. The Cretaceous/Paleogene (K/Pg) Mass Extinction 66 million years ago (Ma) catalyzed the diversification of fish in the open ocean. Cretaceous oceans (>66 Ma) were relatively devoid of fish teeth, and at the K/Pg, fish abundance declined only in the Atlantic Ocean, while in the Pacific, fish abundance stayed constant or increased immediately following the extinction. Yet the event caused a global shift in the marine vertebrate community, with the relative abundance of teeth increasing compared to that of denticles in marine sediments. Further, the size structure of the fish tooth assemblages shifted towards larger, rather than smaller individuals, suggesting that the group was resilient to the extinction event. Bony fishes rose to ecological dominance in the open ocean following the K/Pg extinction, rapidly radiating in morphological diversity after the extinction, while other open ocean groups lagged behind. Extreme global warmth in the Early Eocene (∼52-48 Ma) is associated with an increase in fish and shark abundance, but not diversity. Fish abundance broadly follows global temperature gradients in the Paleogene (66-20 Ma), with the highest abundance of fish in the warmest part of the Cenozoic. The most recent 20 million years is characterized by highly variable ichthyolith production and low abundances of sharks and other elasmobranchs in the gyres. This shift is temporally correlated with the diversification of open-ocean whales and seabirds, groups which may have out-competed sharks for fish prey in the modern open ocean. Together, these results show that that fishes were consistently able to adapt to Cenozoic global change, both ecologically and evolutionarily, allowing the Cenozoic to truly become an "Age of Fishes".
Year of Publication: 2016
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 11 Paleontology, Vertebrate; 12 Stratigraphy, Historical Geology and Paleoecology; Adaptive radiation; Atlantic Ocean; Biodiversity; Biologic evolution; Cenozoic; Chordata; Communities; Concentration; Cretaceous; DSDP Site 596; Deep Sea Drilling Project; Dentition; East Pacific; Fish; Fish scales; IPOD; Ichthyoliths; K-Pg boundary; Leg 198; Leg 208; Leg 91; Lower Paleocene; Marine environment; Mass extinctions; Mesozoic; Microfossils; Morphology; North Pacific; Northwest Pacific; ODP Site 1209; ODP Site 1262; Ocean Drilling Program; Pacific Ocean; Paleo-oceanography; Paleocene; Paleoecology; Paleoenvironment; Paleogene; Paleogeography; Pelagic environment; Range; Reworking; Shatsky Rise; Size; South Atlantic; South Pacific; Southeast Pacific; Stratigraphic boundary; Teeth; Tertiary; Upper Cretaceous; Vertebrata; Walvis Ridge; West Pacific
Coordinates: S235113 S235111 W1653916 W1653917
N323900 N324000 E1583100 E1583000
S271100 S271100 E0013500 E0013400
Record ID: 2019052285
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute.