What Is a Bite Mark on Bone? Evidence of an Encounter, Not Always a Hunt

Feeding traces on bone fall into recognisable categories that reflect how a tooth met the surface. Punctures are round or oval holes made by a tooth pressed straight in, and their depth and spacing constrain the size and arrangement of the teeth involved. Scores are linear grooves made by a tooth dragged across the surface, frequently in parallel sets that record several teeth moving together, and the spacing between them measures the gap between teeth in the jaw. Pits are shallow depressions without penetration. Furrows are broad and deep, made where a tooth was drawn along a ridge. Damage to the ends of bones, where the material is softer and marrow is accessible, is common and indicates the parts of a carcass that were worked hardest. The cross-section of a mark distinguishes a tooth from a tool or from later damage.

Assigning a mark to an animal is possible in some cases and rarely certain:

• •Tooth spacing, since parallel scores record the gap between adjacent teeth and can be matched against jaws
• •Puncture size and shape, which relate to tooth cross-section and constrain the animal's size
• •Serration marks, since teeth with serrated edges leave fine striations within a groove that identify the tooth type
• •The presence of a shed tooth alongside the bone, which is the strongest evidence and does occur, since teeth were replaced continuously and broke off during feeding
• •Which animals of appropriate size are known from the same rocks, which narrows the candidates
• •Force required, estimated from the depth of penetration into bone, which very few animals could achieve

The distinction matters and the marks alone rarely settle it, which is the central difficulty in this evidence. A bite delivered to a living animal and a bite delivered to a carcass look the same on bone, since the tooth does not know the difference. The one decisive indicator is healing, since bone damaged during life and survived shows remodelling around the injury, which establishes both that the animal was alive and that it escaped. Such specimens exist and are prized, including healed bite damage on the tail and face bones of several species. Absent healing, the interpretation depends on circumstance. Marks concentrated on parts with little meat suggest a carcass worked over late, since a predator eating first takes the best parts. Marks from several different tooth sizes suggest sequential visitors. In most cases the honest statement is that an animal was eaten, without specifying by whom or when.

Feeding damage is one of several kinds of trace a bone can carry, and separating them is the first step in any interpretation. Breakage from sediment compaction during burial produces fractures with distinctive edges, since bone broken while fresh behaves differently from bone broken after it has dried and mineralised, and the difference is visible in the fracture surface. Weathering before burial produces cracking along the grain and flaking of the surface, and the stages of that process are well documented and indicate how long a bone lay exposed. Trampling leaves shallow scratches that can resemble tooth marks and are distinguished by their randomness of orientation and their shallow cross section. Insect and invertebrate damage produces characteristic pits and tunnels, and specific traces are attributed to beetles and to other scavengers of dry remains. Root etching leaves branching shallow channels. A specimen typically carries several of these at once.

Despite the difficulties, accumulated evidence supports several conclusions. Bite marks are common on some prey species and rare on others in the same deposits, which indicates selection rather than random encounter. Marks attributable to the largest predators appear on bones of the largest available prey, which is unsurprising and worth having as evidence rather than assumption. Cannibalism is indicated in several species by marks matching the animal's own tooth arrangement, which does not distinguish fighting from scavenging a dead conspecific and does establish the contact. Damage to bone that penetrates deeply is uncommon, which fits reconstructions indicating that most large predators avoided bone where possible, with a small number of exceptions whose teeth and jaw mechanics were built for crushing. And the overall frequency of feeding damage is low, which mainly reflects preservation rather than how often animals were eaten.

Punctures, parallel scores and furrows record tooth size, spacing and serrations, which narrows the maker without usually identifying it, and a shed tooth alongside is the strongest evidence. A bite on a living animal and on a carcass look identical unless the bone healed, which is why healed damage is so valuable. Marks on low-value parts suggest a carcass worked over late.