Human vs Animal Skull: How to Tell, and What to Do If It Might Be Human

The first steps are the same almost everywhere, and they are simple. Stop handling it. Leave the skull, and any bones or objects near it, exactly where they are. Keep other people and animals away from the spot. Call local police or law enforcement, then follow the instructions of the medical examiner, coroner or state archaeologist when they become involved. Authorities may bring in a forensic anthropologist to look at the remains.

The details differ from place to place. Florida's Division of Historical Resources says to leave remains and nearby items in place and not to allow unauthorized removal. Mississippi's Department of Public Safety tells people to call law enforcement after coming across suspected human remains. In Oregon, ORS chapter 146 bars moving suspected human remains without permission in a death that is being investigated. Wherever you are, the local police, coroner or medical examiner for the place where the remains lie is the right first contact.

It helps to remember who this might be. A human skull belonged to a person, someone's relative or ancestor, and it deserves care while the right people take over. Our found human bones story covers the reporting windows, federal and tribal land, and the rules in Mexico and Latin America.

Once you know what to do, the curiosity question is fair: how do specialists tell? They compare a handful of features, and the University of Hawaiʻi's anatomy and physiology text and the University of Central Florida's anthropology text describe the main ones.

A modern human skull has a large, rounded braincase sitting over a relatively short, flat face. The eye sockets, or orbits, face forward. Below the mouth there is a projecting bony chin, which the University of Central Florida text identifies as unique to *Homo sapiens* among the human species it compares. Underneath the skull, the foramen magnum, the opening where the spinal cord passes through, sits near the center of the skull base.

The position of that opening is worth a closer look. The Smithsonian National Museum of Natural History shows the foramen magnum near the center in a human, and farther toward the rear in a dog and a chimpanzee.

None of these features works as a test on its own. Human skulls vary, and age, ancestry, disease, damage and fossil status can all change how one looks. Treat the list as a way to understand what experts compare, not as a way to rule a person out. For more on the parts of a human skull, see our human skull facts.

Forensic anthropologists point to large mammals as the usual cause of confusion. The American Board of Forensic Anthropology says bear bones, especially paws, are commonly mistaken for human bones by untrained people. A forensic anthropology teaching text lists deer, bears, large dogs and pigs as the animals most often confused with adult human bones, and notes that small animals may resemble juvenile or fetal human remains.

Each of those animals leaves its own clues. A deer skull has no upper incisors, according to the Internet Center for Wildlife Damage Management. In a National Park Service comparison, dog and bear skulls both have carnassial teeth, specialized cheek teeth for shearing and cutting meat, while omnivores such as the bear also have molars with broad grinding surfaces. Our story on the bear skull shows what that heavy, mixed set of teeth looks like.

Two comparisons come up again and again, and both are easy to make with the whole skull in view.

A cat skull is usually much smaller than a human skull. It has a short animal muzzle, large forward-facing eye sockets of the kind predators have, and prominent, sharp canines. A human skull has a far larger rounded braincase compared with the face, small canines and a projecting chin. Cats vary, so comparing with a verified specimen is safer than going by size alone. The cat skull identification story goes further.

Most dog skulls have an elongated muzzle, large canines and a foramen magnum set farther toward the back than in a human. Dogs vary enormously by breed, though, and a greyhound and a pug do not share the same proportions. What stays human is the large rounded braincase, the short flat face and the chin.

If the skull is clearly an animal's, the identification stories in this series pick up from here. The fox skull and coyote skull stories cover two wild relatives of the dog. The opossum skull and raccoon skull stories cover two more skulls people ask about. And the bear skull and beaver skull stories deal with the big skull with heavy teeth and the rodent skull with orange ones.

Teeth are some of the most useful evidence on a skull, and also some of the easiest to misread. Most adults have 32 permanent teeth, according to the Cleveland Clinic: eight incisors, four canines, eight premolars and 12 molars. Written as a dental formula, that is 2.1.2.3 in each quarter of the mouth.

A full set of 32 can support a human identification, but the count alone is unreliable. People lose teeth, wisdom teeth may never come in, dental treatment changes a mouth, and age and damage do the rest. A human skull with 28 teeth is still a human skull.

Animal teeth tend to be more specialized. The Smithsonian's guide and the National Park Service lesson describe carnivores with cutting or shearing teeth, plant eaters with broad grinding molars, and omnivores that combine several kinds. A human skull, by comparison, has smaller canines than a cat or a dog.

Sometimes the find is not a skull at all but a long bone or a rib, and the same caution applies. Specialists assess a long bone by its overall shape, size, the shape of its shaft, its joint ends, its muscle attachments, its maturity and even its microscopic structure. Human limb bones reflect habitual walking on two legs, and they are generally more slender than the weight-bearing limb bones of many large four-legged animals.

Age can mislead in both directions. A small adult animal may have fully fused growth plates, while a young human may still have unfused epiphyses, the separate ends of a growing bone. A small bone that looks grown-up can belong to an animal, and a bone that looks unfinished can belong to a child.

Ribs carry clues too. A University of New Mexico forensic anthropology teaching module describes human ribs as tending toward a C shape, while many animal ribs are straighter. Humans normally have 12 pairs of ribs, although individuals vary; sheep have 13 pairs.

Fragments and weathered pieces are hard even for experts, and the American Board of Forensic Anthropology advises that suspected human bone be left for a forensic anthropologist. For the full count of what a human skeleton contains, see how many bones are in the human body.

If the authorities, or the skull's own features, make clear that you are holding an animal's skull, the questions change to what it is and whether you may keep it. Our story on what to do if you found an animal skull covers identification and the federal and state rules, which vary by species and place; it is general information, and the state wildlife agency has the answer for your find. When cleaning is allowed, how to clean an animal skull explains safe methods.

These questions come up once the first steps are clear.

If the skull or bone might be human, the next step is a phone call, and found human bones explains what follows. If it is an animal's, found an animal skull and the cat, fox, coyote, opossum, raccoon, bear and beaver skull stories help name it. And for the human side of the comparison, human skull facts shows what a skull is made of.

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