Chondrichthyan specimen data from the Florida fossil record

As of September 2019, the Florida Museum of Natural History (FLMNH) had a
curated collection of 117,449 chondrichthyan specimens from Florida,
spanning the Eocene through the Pleistocene. Herein, I evaluated the
completeness of the chondrichthyan fossil record from Florida based on the
FLMNH collection, while analyzing patterns in taxonomic and
ecomorphological diversity. At least 70 chondrichthyan taxa were
recognized, representing 10 orders, 26 families, and 42 genera; of which,
20 taxa represent first occurrences from Florida. A sample of 107,698
specimens was organized into 12 time bins to analyze taxonomic and
ecomorphological diversity, with an expectation that diversity patterns
would correspond with global climate events (e.g., the Eocene-Oligocene
Transition and the Middle Miocene Climatic Optimum). However, diversity
patterns were obscured by pervasive sampling bias, attributable to
variable collection methods, research prioritizations, and regional
lithologic controls. Sampling is particularly poor for smaller specimens
and older geologic units (e.g., the Paleogene). Despite incomplete
sampling of the Florida chondrichthyan fossil record, there was an
apparent turnover along the Atlantic and Gulf coastal plains from a
lamniform to carcharhiniform dominated chondrichthyan fauna that occurred
during the Eocene. This turnover corresponded with the extinction of many
lamniform taxa with grasping-dominated dentition types (e.g.,
Brachycarcharias, Jaekelotodus, and Macrorhizodus). Selachian taxa that
survived the late Eocene extinctions were predominantly represented by
cutting-dominant dentition types. Since cutting aids in the dismemberment
of prey, this may reflect a macroevolutionary trend towards active
predation and scavenging on larger prey, such as marine mammals, teleost
fish, and other sharks.