Tullimonstrum

Tullimonstrum, commonly known as the Tully Monster, is an extinct genus of soft-bodied bilaterian that lived approximately 307 million years ago during the Pennsylvanian subperiod of the Carboniferous period. Its fossils are exclusively found in the Mazon Creek fossil beds of Illinois, USA. The Tully Monster remains one of the most enigmatic and peculiar fossils ever discovered, leading to extensive debate regarding its phylogenetic classification.

Description

Tullimonstrum was characterized by its long, tubular body, which ended in a tail fin. Its most distinctive feature was a long, proboscis-like appendage that extended from the front of its body, terminating in a mouth with sharp teeth. This creature also possessed a pair of stalked eyes, which were situated on either side of its body, providing it with a wide field of vision. The body of Tullimonstrum was segmented, suggesting some degree of flexibility and mobility.

Classification

The classification of Tullimonstrum has been a subject of debate among paleontologists. Initially, it was difficult to place the Tully Monster within the established tree of life due to its unique morphological features. Over the years, various hypotheses have been proposed, including affiliations with mollusks, arthropods, and even vertebrates. Recent studies, particularly those involving the analysis of its eye structure and the chemical composition of its fossils, suggest that Tullimonstrum may have been a vertebrate, possibly related to lampreys or other jawless fish. However, the lack of definitive evidence means that its exact place in the tree of life remains uncertain.

Habitat

The Tully Monster inhabited a shallow, marine environment that was part of a large coastal estuary system. The Mazon Creek area, where its fossils are found, was a tropical estuary that supported a diverse ecosystem, including various plants, invertebrates, and vertebrates. The presence of Tullimonstrum in this environment suggests it was a predator or scavenger, feeding on small organisms or organic debris.

Fossil Record

Fossils of Tullimonstrum are primarily found in the Mazon Creek fossil beds, a Lagerstätte known for its exceptional preservation of soft-bodied organisms. The unique conditions of the Mazon Creek area allowed for the rapid burial and mineralization of organisms, preserving fine details of their anatomy. Tullimonstrum fossils are among the most iconic and well-studied specimens from this site.

Scientific Significance

The Tully Monster holds significant scientific interest due to its unusual morphology and the mystery surrounding its classification. Its study provides insights into the diversity of life during the Carboniferous period and the evolutionary history of soft-bodied organisms. Additionally, Tullimonstrum is an important symbol of Illinois, having been designated as the state fossil in 1989.

See Also

• Mazon Creek fossil beds
• Lagerstätte
• Carboniferous period
• Vertebrate
• Lamprey