Bones hold a unique appeal, serving as silent records of past life and ecosystems. Discovering a bone can spark immediate curiosity about its origin, prompting questions about what creature it once belonged to and how it came to be in its found location.
First Steps in Bone Identification
When you encounter a bone, begin by observing its general characteristics. Consider the bone’s overall size and shape, noting if it appears thick and robust or slender and delicate. The texture of the bone’s surface, whether it feels porous, dense, or smooth, can also provide insight into its possible origin.
For example, the presence of a smooth medullary surface in the interior of a long bone suggests it might be from a non-human animal. The weight of the bone offers another important clue; some bones are surprisingly light, while others feel remarkably heavy for their size. Additionally, the color of the bone can indicate its age, the type of soil it was buried in, or whether it has been exposed to the elements or fire.
Telling Human Bones from Animal Bones
Distinguishing human bones from animal bones requires attention to specific anatomical differences. Human bones generally possess a lower density and are more porous than those of many large animals. Human cranial vault bones also typically have thicker diploë relative to the outer cortical bone compared to the thinner, more compact vault bones found in non-human animals.
The shape and structure of certain bones are particularly indicative of human or animal origin. Human skulls feature a large, bulbous cranial vault that accommodates a larger brain relative to body mass, alongside a comparatively small face. In contrast, many animal skulls have smaller cranial vaults and more pronounced facial projections. The foramen magnum, where the spinal cord exits, is positioned inferiorly (underneath) in humans for upright posture, whereas it is typically more posterior in quadrupedal animals.
Differences in the pelvis and limb bones also offer clear distinctions. The human pelvis is broad and bowl-shaped, an adaptation for bipedal locomotion, while most animals possess a longer, more blade-like pelvis. Human long bones, such as the radius and ulna in the forearm, remain unfused, allowing for a wide range of motion. In many animals, these bones, or the tibia and fibula in the lower leg, are often fused or significantly modified to support their specific modes of locomotion, such as weight-bearing in quadrupeds. Bear paws, for example, can surprisingly mimic human hands and feet due to their similar overall size and shape, but closer examination reveals differences in phalangeal structure and the presence of claws. The heads of bear proximal phalanges often have a deep V-shaped groove, unlike the relatively smooth, flat shape of human articular surfaces.
Classifying Animal Bones by Type
Once a bone is determined to be animal, further classification can often narrow down the type of creature it came from by examining broad skeletal characteristics. Mammalian bones are generally dense with distinct marrow cavities within their long bones. The lower jaw of mammals is unique, consisting of a single bone, the dentary, which connects directly to the skull. This contrasts with other vertebrates that have multiple bones in their lower jaw.
Bird bones are notably lightweight and often hollow, containing air sacs that contribute to their ability to fly. Despite their light appearance, bird bones can be denser than those of similarly sized mammals, providing strength without excessive weight. Many bird vertebral sections are fused, forming a rigid spinal column that supports flight.
Fish skeletons, in contrast, are typically composed of many small, sometimes translucent, bones that are designed for movement through water. The vertebral column of a fish provides the main supporting structure for the muscles used in swimming. Fish bones are generally lighter and more flexible than those of other vertebrates, and some fish, like sharks, have skeletons primarily made of cartilage rather than calcified bone.
Reptile bones are generally well-ossified, providing a strong framework, though their bone structure can vary significantly depending on the species. Many reptiles exhibit kinetic skulls, allowing for movement within the skull to aid in swallowing large prey. Amphibian skeletons, particularly those of frogs, are adapted for leaping and swimming with elongated hind limbs and a robust forelimb structure. Their bones are hollow and lightweight, similar to birds, but their overall skeletal arrangement reflects their unique terrestrial and aquatic lifestyles.
Where to Go for Further Identification
If you find a bone and suspect it might be human, the appropriate first step is to contact your local law enforcement agency, such as the police or sheriff’s department. Disturbing the remains could compromise potential forensic evidence or archaeological contexts. Authorities can ensure proper investigation and handling of the remains, especially if they are of human origin.
For bones clearly identified as animal, or if you require more specialized identification, several resources are available. Natural history museums often have extensive comparative collections and expert staff who can assist with identification. University biology or anthropology departments, particularly those with forensic anthropology programs, can also be valuable resources. Online identification forums or academic websites dedicated to osteology might offer guidance, but professional verification is always recommended for certainty. Respectful handling of all found remains and adherence to local regulations regarding their collection and possession are important considerations.