Finding ancient dinosaur remains in the field connects a person directly to deep geological time. Paleontology, the study of ancient life, relies on finding and properly identifying these preserved traces of organisms. Identifying a potential dinosaur bone requires understanding what the fossil looks like, how it formed, and where it is found. Discovering a genuine fossil involves a methodical approach blending geological knowledge with a careful examination of physical properties.
The Fossilization Process
A dinosaur bone found today is a mineralized replica resulting from permineralization. After an animal dies, its remains are quickly buried by sediment like mud or sand. Soft tissues decompose, leaving hard parts, such as bone, protected from erosion. Groundwater, rich in dissolved minerals like silica, calcite, or iron oxides, seeps into the microscopic pores within the buried bone.
These dissolved minerals precipitate and crystallize within the original porous structure. This process gradually replaces the organic material, turning the bone to stone over millions of years. The resulting fossil retains the original shape and internal structure but is dense and heavy due to the infilling minerals.
Differentiating Fossilized Bone from Rock
The most reliable way to identify a true fossil is by looking for the preserved biological structure. A broken or exposed surface of a fossilized bone often reveals a distinctive webbed or spongy texture known as trabecular bone. This internal structure, with its network of canals and pores, is absent in ordinary rock or mineral concretions, which tend to have a compact, uniform, or crystalline interior.
The exterior of a fossil bone fragment frequently displays a rougher, more porous texture compared to a naturally weathered rock. These small openings, called porosity, are remnants of the original bone’s vascular system filled with minerals during permineralization. Fossilized bone is noticeably heavier than a modern bone of similar size because the mineral infilling increases the overall density.
Color is a less reliable indicator, determined by the specific minerals that replaced the organic material. Fossils can range from black to dark brown, reddish-brown, or light tan, depending on whether iron oxides, manganese, or silica were the replacing agents. Some field workers use the “tongue test,” where the porous surface of a fossilized bone will slightly stick to the tongue due to its absorption capacity, a property not shared by most smooth rocks.
Identifying the Geologic Context
The physical location and age of a find provide a powerful filter for identification, as dinosaur fossils are found only within specific geological settings. True dinosaur remains date exclusively from the Mesozoic Era (252 to 66 million years ago), encompassing the Triassic, Jurassic, and Cretaceous Periods. Finding a bone in rock layers from the Cenozoic Era, which began after the dinosaurs’ extinction, rules out a dinosaur find.
Dinosaur fossils are almost always found embedded within sedimentary rock formations, such as sandstone, shale, or siltstone. These rock types form from the accumulation and cementation of sediment in environments like ancient floodplains, rivers, or lakes. If a potential fossil is found in igneous rock (formed from cooled magma) or metamorphic rock (altered by heat and pressure), it cannot be a dinosaur bone, as these processes destroy organic remains.
Common Misidentifications and Look-Alikes
Many objects are mistakenly identified as dinosaur bones, with mineral concretions being the most frequent look-alike. Concretions are masses of mineral matter, often iron or calcium carbonate, that form within sedimentary rock and can weather out into bone-like shapes. The key difference is that the interior of a concretion is uniformly mineral or crystalline and lacks the organized internal structure of bone tissue.
Other common misidentifications include oddly shaped rocks, pieces of petrified wood, and the bones of modern animals. Petrified wood, while also permineralized, exhibits the characteristic rings and grain of tree tissue rather than the trabecular structure of bone. Modern bones, or sub-fossils, are distinguished by their light weight and lack of full mineralization. Marine reptile fossils, such as those from ancient turtles or mosasaurs, are also found in Mesozoic rocks but require expert knowledge to distinguish from dinosaur bones.
Next Steps After Discovery
If a likely dinosaur bone is discovered, the most important action is to leave the specimen exactly where it was found. Moving or collecting the bone destroys its geological context, which is essential scientific information regarding the original burial environment and its relationship to other potential fossils. The precise location of the find should be documented immediately using a GPS device for coordinates, along with photographs taken from multiple angles.
After documentation, the next step is to contact a professional paleontologist at a local natural history museum, a university geology department, or a government land management agency. These experts can verify the find and manage the proper excavation, which requires specialized tools and techniques to preserve the fossil and all surrounding data. The legal status of the land determines ownership, but responsible reporting ensures the discovery contributes to scientific knowledge.