RECONSTRUCTING THE EXTINCTION OF THE
GIANT MEGALODON SHARK (CARCHAROCLES
MEGALODON) Pimiento, Catalina, Florida Museum of Natural History,
University of Florida, 1659 Museum Road, P.O. Box 117800,
Gainesville, FL 32611;
Balk, Meghan, Department of
Biology, University of New Mexico, Albuquerque, NM
87131;
Celements, Christopher, Department of Animal and
Plant Sciences, University of Sheffield, Western Bank,
Sheffield S10 2TN UK
Top predators play a key role in structuring the world’s
ecosystems. Their extinction can trigger cascading effects
through entire food webs and impact ecosystem structure and
function. Examining the fossil record to understand
extinctions of ancient top predators may provide insight for
conservation of modern organisms. Potential mechanisms
underlying the extinction of the shark
Carcharocles megalodon, the largest marine predator to ever exist, remain
largely unknown. Based on the fossil record, we know that it
lived from the middle Miocene to the Pliocene, could reach
up to 18 meters in length, and had a global distribution. In
spite of this, the time of its extinction and its body size and
geographic distribution patterns have never been examined
before. Here, we present an estimate of the date of extinction
of
C. megalodon, and an assessment of changes in its body
size and geographic distribution throughout geologic time, in
order to understand the trajectory of its extinction. We use
statistical methods to establish the most likely age of
extinction, tooth measurements of various global collections
to estimate body size, and occurrence data to calculate
distribution range over time. The results from this study will
provide insights into the extinction of one of the ocean's
largest top predators. Most importantly, they will allow
greater predictive power in addressing declining populations
of extant sharks and assist in targeting conservation efforts
directed at mitigating large shark extinction risk.
BODY SIZE CHANGE OF CARCHAROCLES
MEGALODON THROUGH TIME IN COMPARISON
WITH CONTEMPORANEOUS MARINE MEGAFAUNABalk, Meghan ,Department of Biology, University of
New Mexico, 167 Castetter Hall, MSC03 2020 1, University
of New Mexico, Albuquerque, NM 87131;
Pimiento, Catalina,
Florida Museum of Natural History, University of
Florida, 1659 Museum Road, P.O. Box 117800, Gainesville,
FL 32611
Body size is a universal measure of all organisms, and is
intrinsically related to an organisms’ ecology. Metabolic rate,
generation time, and trophic level have previously been
shown to scale with body size in some taxa. These
relationships can be used to broadly characterize ecologies of
past animals. Paleomarine megafauna are understudied, yet
underwent reorganization in response to both climatic change
and extinction of apex predators, which is similar to
problems facing modern marine ecosystems. Here, we
explore body-size estimates for
Carcharocles megalodon,
test the evolution of body size in
C. megalodon, and compare
trends in body-size change of
C. megalodon to that of other
marine megafauna. From eight museums, we collected
records of
C. megalodon with a temporal span from middle
Miocene through late Pliocene. Ultimately, we seek to
understand fundamental characteristics of the paleoecology
of this marine apex predator, as well as community-level
changes in body-size distributions in the marine realm.
Future research will explore how these marine communities
changed in response to the extinction of
C. megalodon in
conjunction with other global abiotic changes, and how these
patterns compare to modern ocean disturbances.
www.flmnh.ufl.edu/files/6813/9085/6747/NAPC_2014_Abstract_Book.pdf
