Microtomographic reconstruction of the head and anterior trunk ("body") limbs of the trilobite Protolenus (Hupeolenus) in ventral view. Credit: Arnaud Mazurier, IC2MP, Univ. Poitiers
Phys.org has an article about an amazing fossil find in Morocco. A recently discovered deposit of Cambrian trilobites is being described as Pompeii-like, in that the fossils were preserved in volcanic ash (like the Roman city of Pompeii). The fossils are preserved with such fidelity that some never before seen anatomical features are seen preserved in 3-D. All the details are in the paper "Rapid volcanic ash entombment reveals the 3D anatomy of Cambrian trilobites" published in the journal Science.
The trilobites, from the Cambrian period, have been the subject of research by an international team of scientists, led by Prof Abderrazak El Albani, a geologist based at University of Poitiers and originally from Morocco. The team included Dr. Greg Edgecombe, a paleontologist at the Natural History Museum.
Dr. Greg Edgecombe said, "I've been studying trilobites for nearly 40 years, but I never felt like I was looking at live animals as much as I have with these ones. I've seen a lot of soft anatomy of trilobites, but it's the 3D preservation here that is truly astounding.
"Rapid volcanic ash entombment reveals the 3D anatomy of Cambrian trilobites"
Editor's summary
Trilobites are probably the best known denizens of the Cambrian Period. Their distinctive fossilized external forms are well recognized from an extensive fossil record spanning the early Cambrian to the Permian extinction. The vast majority of trilobite fossils display only external morphology, however, leaving much unknown about their internal morphology. El Albani et al. describe several trilobite fossils created by rapid death and preservation due to an underwater pyroclastic flow. This preservation created three-dimensional fossils with a remarkably well-preserved anatomy. This enhanced understanding of trilobite anatomy has revealed several new features and provided key insights into crown group euarthropods. —Sacha Vignieri
Abstract
Knowledge of Cambrian animal anatomy is limited by preservational processes that result in compaction, size bias, and incompleteness. We documented pristine three-dimensional (3D) anatomy of trilobites fossilized through rapid ash burial from a pyroclastic flow entering a shallow marine environment. Cambrian ellipsocephaloid trilobites from Morocco are articulated and undistorted, revealing exquisite details of the appendages and digestive system. Previously unknown anatomy includes a soft-tissue labrum attached to the hypostome, a slit-like mouth, and distinctive cephalic feeding appendages. Our findings resolve controversy over whether the trilobite hypostome is the labrum or incorporates it and establish crown-group euarthropod homologies in trilobites. This occurrence of moldic fossils with 3D soft parts highlights volcanic ash deposits in marine settings as an underexplored source for exceptionally preserved organisms.
