EXPLORING THE PSEUDOPLANKTONIC LIFESTYLE OF TRAUMATOCRINUS

 

Traumatocrinus sp. Wöhrmann 1889 (Echinodermata, Crinoidea, from Late Triassic (Carnian) Xiaowa Formation of the Guanling area (Guizhou, Southwest China) (Photo by Jordi Sanchez).

The study of Traumatocrinus sp., a unique crinoid from the Late Triassic period, reveals fascinating insights into its lifestyle and ecological role. Here are some key points about this intriguing organism:

• Pseudoplanktonic Lifestyle: Traumatocrinus is characterized by its pseudoplanktonic nature, meaning it was not entirely free-floating but rather attached to driftwood. This adaptation allowed it to thrive in the marine ecosystems of the Late Triassic, particularly within the Xiaowa Formation of Southwest China. The ability to adjust its filtration fan based on current and drifting regimes was crucial for its survival in these environments.
  
• Colony Structure and Social Living: Colonies of Traumatocrinus could consist of more than 150 individuals, all anchored to logs of driftwood by root cirri. This communal living likely provided advantages in feeding efficiency and reproductive success, as the collective structure could enhance the capture of planktonic food sources. The large size of the colonies also suggests a well-adapted strategy for thriving in a dynamic marine environment.

 

Colony of Traumatocrinus hsui attached to driftwood, drawn after in situ occurrence; the crinoids preferentially attached to tips of log; crowns of similar size, but columns differ in length to reach different depths, length of driftwood 3.3 m, Xiaowa Formation, Ladinian-Carnian boundary, Guanling, China (adapted from Hagdorn & others, 2004).

• Impressive Size and Growth: The stem of Traumatocrinus could exceed 11 meters in length, showcasing its remarkable size. This extensive structure would have played a vital role in maintaining buoyancy and stability while attached to drifting logs. The large filter fans, formed by numerous arms and pinnules, would have been essential for maximizing feeding opportunities in the nutrient-rich waters.
• Ecological Impact and Evolution: After the end-Carnian extinction event, the ecological niche that Traumatocrinus occupied was taken over by other crinoids like Seirocrinus and Pentacrinites. These organisms evolved similar adaptations to thrive in the changing marine environments of the Norian period, demonstrating the evolutionary pressures and ecological shifts that occurred during this time.
• Taphonomy and Fossil Preservation: The preservation of Traumatocrinus remains is particularly noteworthy, with fossils found in laminated calcareous mudstones and claystones. This indicates a unique taphonomic process where the crinoids were sealed by bacterial mats, contributing to their exceptional fossilization potential. The black shales of the Xiaowa Formation provided ideal conditions for preserving these delicate structures.

 

Traumatocrinus sp. Wöhrmann 1889) (Photo by Jordi Sanchez).

 

• Historical Context and Taxonomy: The classification of Traumatocrinus has evolved over time, with various researchers attributing it to different taxonomic groups. Initially regarded as a junior synonym of Encrinus, its systematic position remains somewhat uncertain, reflecting the complexities of crinoid evolution and the challenges faced by paleontologists in accurately categorizing these ancient organisms.

In summary, the study of Traumatocrinus not only enhances our understanding of crinoid evolution but also sheds light on the ecological dynamics of the Triassic seas. Its pseudoplanktonic lifestyle, impressive size, and unique adaptations make it a remarkable subject of paleontological research, offering insights into the ancient marine ecosystems that once thrived in our planet's history.

References: 

Hess, H. (2010). Treatise Online, no. 16, Part T, Revised, Volume 1, Chapter 19: Paleoecology of pelagic crinoids. Treatise Online.

Hagdorn, H., Wang, X., Bachmann, G. H., Cuny, G., Sander, M., & Wang, C. (2004). Kolonien der pelagischen Seelilie Traumatocrinus aus der obertriassischen Xiaowa-Formation von Guanling (Süd-China, Provinz Guizhou). Stachelhäuter, 3, 17-30.

Hagdorn, H., Wang, X., & Wang, C. (2007). Palaeoecology of the pseudoplanktonic Triassic crinoid Traumatocrinus from Southwest China. Palaeogeography, Palaeoclimatology, Palaeoecology, 247(3-4), 181-196.