Possible notochordal chordoma in a fossil fish from the Late Cretaceous of Lebanon.

OBJECTIVE

To describe a case of an expansive endocavitary lesion at the level of the caudal tract of the vertebral column of a juvenile fish (Pycnodont) from the Late Cretaceous (Cenomanian) of Lebanon (Hjoula).

MATERIALS: The specimen is part of the Paleontological Collection of the University Museum of Chieti, Italy, Inventory Number P #23752.

METHODS

The specimen was observed macroscopically, as well as under the stereo-microscope (Leica Wild M 8); aspersion with ethanol and razing light were used to improve the observations and to take micro-photos.

RESULTS

The fossil juvenile fish has a visibly altered macroscopic anatomical morphology at the level of the caudal part of the vertebral column, which is pathological in comparison with the normal anatomy of the Pycnodonts.

CONCLUSIONS

Although diagnosis cannot be certain, comparative analysis notes morphological and topographic affinity between the paleopathological case described here and notochordal chordoma, which affects some living fish.

SIGNIFICANCE: This lesion represents the first case of a nonosseous tumor in a fossil fish, and suggests that this type of neoplasm was among the first of the neoplastic diseases to appear on Earth.

LIMITATIONS: Diagnosis rendered from fossil remains is complex and is further limited by the rarity of the condition in the past.

SUGGESTIONS FOR FURTHER RESEARCH: Continued comparative analysis of bony changes noted in this specimen with other fossil and living fish will contribute to our understanding of disease in the Earth's earliest inhabitants.