Crotalocephalus and Dicranurus monstrous Trilobite from Morocco (720.2 grams)
Trilobite Death Assemblage with Crotalocephalus and Dicranurus monstrous
Trilobites, an early arthropod relative of spiders, horseshoe crabs, and scorpions, preserved in this level of detail only occurred as a result of very sudden underwater landslides called turbidite sequences, which ravaged the early earth when the continents were still very much on the move. The contorted body positions of the trilobites demonstrate a final fight against being buried alive.
Here, we see two very different trilobite lineages caught in the same ill-fated struggle for their lives.
The unornamented Crotalocephalus were likely adapted for life close to the sea floor. Crotalocephalus, a member of the Phacopida, is actually incredibly derived: it has re-evolved small eyes, something very different from its phacopid ancestors.
By contrast, the elaborate Dicranurus monstrosus, a member of the tiny-eyed Odontopleurid trilobite family, likely glided above the sea floor at the dark end of the continental slope, where eyes were not terribly important. The bulbous mass between the eyes, called the glabella, represents the entire stomach cavity of a trilobite. The very different shapes and sizes in these two sleciea' stomachs indicates very different behavior and lifestyle.
Species: Crotalocephalus and Dicranurus monstrous
Age: Upper Devonian 400-380 MYO
Location: Djbel Ougrat, Morocco
Size: 4 x 4 x 1 inches
Weight: 365.5 grams