Paleontological research on predation has been expanding rapidly in scope, methods, and goals. The growing assortment of research strategies and goals has led to increasing differences in sampling strategies, types of data collected, definition of variables, and even reporting style. This methodological overview serves as a starting point for erecting some general methodological guidelines for studying the fossil record of predation. I focus here on trace fossils left by predators in the skeleton of their prey, arguably one of the most powerful sources of direct data on predator-prey interactions available in the fossil record. A critical survey of sampling protocols (data collecting strategy, sieve size, and sample size) and analytical approaches (predation intensity metrics, strategies for evaluating behavioral selectivity of predators, and taphonomic tests) reveals that various approaches can be fruitful depending on logistic circumstances and scientific goals of paleoecological projects. Despite numerous caveats and uncertainties, trace fossils left by predators on skeletons of their prey remain one of the most promising directions of research in paleoecology and evolutionary paleobiology.

The fossil record of predation: an overview of analytical methods

The fossil record yields abundant data on the interaction between drilling predators and their shelled prey. Predatory drill holes may date to the late Precambrian (Bengtson and Zhao, 1992) and have been reported from various Paleozoic assemblages (e.g., Sheehan and Lesperance, 1978; Smith et al., 1985; Conway Morris and Bengtson, 1994). Paleozoic drill holes have been reported primarily from brachiopods, although gastropods (Rohr, 1991) and bivalves (Kowalewski et al., 2000; Hoffmeister et al., 2001) also exhibit apparent predatory drill holes. In most cases, the identities of the Paleozoic drilling predators are unknown; platyceratid gastropods documented in association with drilled Paleozoic crinoids and blastoids appear to have been parasitic (Baumiller, 1990, 1996, 2001).

The Fossil Record of Drilling Predation on Bivalves and Gastropods

Mesozoic and Cenozoic evolution of predators involved a series of episodes. Predators rebounded rather rapidly after the Permo-Triassic extinction and by the Middle Triassic a variety of new predator guilds had appeared, including decapod crustaceans with crushing claws, shell-crushing sharks and bony fish, as well as marine reptiles adapted for crushing, smashing, and piercing shells. While several groups (e.g., placodonts, nothosaurs) became extinct in the Late Triassic crises, others (e.g., ichthyosaurs) survived; and the Jurassic to Early Cretaceous saw the rise of malacostracan crustaceans with crushing chelae and predatory vertebrates—in particular, the marine crocodilians, ichthyosaurs, and plesiosaurs. The late Cretaceous saw unprecedented levels of diversity of marine predaceous vertebrates including pliosaurids, plesiosaurs, and mosasaurs. The great Cretaceous-Tertiary extinction decimated marine reptiles. However, most invertebrate and fish predatory groups survived; and during the Paleogene, predatory benthic invertebrates showed a spurt of evolution with neogastropods and new groups of decapods, while the teleosts and neoselachian sharks both underwent parallel rapid evolutionary radiations; these were joined by new predatory guilds of sea birds and marine mammals. Thus, although escalation is sometimes cast as an ongoing “arms race,” in actuality the predatory record shows long interludes of relative stability puncturated by episodes of abrupt biotic reorganization during and after mass extinctions. This pattern suggests episodic, but generally increasing, predation pressure on marine organisms through the Mesozoic-Cenozoic interval. However, review of the Cenozoic record of predation suggests that there are not unambiguous escalatory trends in regard to antipredatory shell architecture, such as conchiolin and spines; nor do shell drilling and shell repair data show a major increase from the Late Mesozoic through the Cenozoic. Most durophagous groups are generalists, and thus it may be that they had a diffuse effect on their invertebrate prey.

Post-Paleozoic Patterns in Marine Predation: Was there a Mesozoic and Cenozoic Marine Predatory Revolution?

Drill holes, used widely by biologists and palaeontologists to study predator-prey interactions, provide rich quantifiable data on drilling carnivores and their victims. A laboratory experiment, involving over 50 individuals of the drilling gastropod Nucella lamellosa (Gmelin) and several hundred individuals of its natural prey, the mussel Mytilus trossulus (Gould), was employed to test the informative value and validity of several drill-hole parameters. The majority of attacks (∼88%) were accomplished by drilling, providing a record of predation intensity that is only slightly underestimated. In three out of nine cases, prey killed without drilling exhibited an incomplete drill hole, so that incomplete muricid drill holes need not record failed predatory attacks. Drill-hole dimensions correlate with predator size, but the size and thickness ofprey shell do not affect drill-hole size. The spatial distribution of drill holes on prey shells does not suggest any obvious site-selective stereotypy in drilling behaviour. The drill-hole morphology is relatively invariant in terms of vertical profile, but highly variable in outline. Although none of the holes produced in the experiment could readily be mistaken for a naticid drilling, the high variability in outline could be misinterpreted (especially if data came from the fossil record) as evidence for presence of multiple types of predators.

Drill holes produced by the predatory gastropod nucella lamellosa (muricidae): palaeobiological and ecological implications

Drilling predation presents a rare opportunity to quantify ecological interactions in the fossil record. Most large-scale studies have focused on temporal rather than spatial patterns. However, spatial variability patterns may both mask secular trends and provide important insights into geographic and environmental gradients in predation. To explore spatial patterns in predation, bulk samples of mollusks were collected from middle Miocene (Burdigalian and Langhian) marine deposits of Europe, including multiple sites from two adjacent bioprovinces: the Boreal Province and Paratethys. Two facies were sampled: fine-grained and coarse-grained siliciclastics. The sampling scheme allows for a comparison of drilling predation at the local scale (within provinces), regional scale (between provinces), and between facies (within and between provinces). In the Miocene of Europe, statistically significant spatial variations in drilling-predation patterns occur locally, regionally, and among facies (these var...

https://www.jstor.org/stable/pdfplus/3515629.pdf

S.E. Graham

Papers

Temporal patterns in the efficiency of naticid gastropod predators during the Cretaceous and Cenozoic of the United States Coastal Plain