Paleontologists have assumed that they could rely on microscopic observation of round and oblong structures, identified as melanosomes, found in the preserved feathers of ancient birds, to accurately identify the birds’ coloring. This is because melanosomes contain melanin, a complex polymer derived from the amino acid tyrosine, that determines skin and feather color. However, recent research involving a fossilized feather from an avian dinosaur known as Gansus yumenensis has cast doubt on that assumption. Rather than appearing on the surface of the feather, melanosomes are shielded by the protein keratin. Only after the keratin has been degraded can the melanosome be examined.

Yet, the microbes involved in the decomposition process required to expose the melanosomes have round and oblong microscopic structures visually indistinguishable from the melanosomes themselves, even under sophisticated microscopic observation. Here, reasonably simple concepts are camouflaged by the scientific topic and its related technical terms. There is no distinct trap in this example, other than the tendency of many students to shut down when faced with unfamiliar, technical language. In more simplified language, the passage presents this issue: Paleontologists cannot rely on the microscopic structure of melanosomes to identify the coloring of ancient birds, because the melanosomes can only be seen if microbes with an indistinguishable structure are also present. So, the observer cannot tell if what they are observing are the melanosomes (which produce the coloring), or microbes (which caused the decomposition).