| Clearly visible within the imprint were the remains of trilobites, extinct marine arthropods. |
| One modification in trilobites might be that the selection was primarily for exoskeletal morphology rather than limb structure. |
| The detailed structure of both exopods and endopods varied, both along the trunk of individual trilobites, and among different taxa. |
| But in fact, there are very distinct patterns found in the fossil record of trilobites. |
| The trilobites comprise a major class-level clade of extinct marine arthropods characterized by calcareous, multisclerite, dorsal exoskeletons. |
| By contrast, the trilobites documented herein are from thrombolitic buildups. |
