Ramskoeldia

Ramskoeldia is a genus of amplectobeluid radiodont described in 2018. It was the second genus of radiodont that found to possess gnathobase-like structures (abbreviated as GLS) and atypical oral cone next to Amplectobelua[1]. It was discovered from the Chengjiang biota of China, the home of numerous radiodont such as Amplectobelua and Lyrarapax.

Ramskoeldia
Temporal range: Chengjiang–Middle Cambrian
Frontal appendages of R. platyacantha and R. consimilis
Scientific classification
Kingdom:
Animalia
Phylum:
Arthropoda
Class:
†Dinocaridida
Order:
†Radiodonta
Family:
†Amplectobeluidae
Genus:
†Ramskoeldia
Cong et al, 2018
Type species
Ramskoeldia platyacantha
Cong et al, 2018
Species
  • R. platyacantha
  • R. consimilis

Ramskoeldia known only from a handful of frontal appendages, gnathobase-like structures (GLSs), disarticulated smooth and tuberculated plates interpreted as parts of their oral cones, as well as fragments of body flaps and head carapace complex. Frontal appendage of Ramskoeldia compose of 16 podomeres (3 shaft podomeres and 13 distal articulated region podomeres), with endites of podomeres 4 to at least podomere 12 bore prominent auxiliary spines. Endites of podomere 4 (first podomere of distal articulated region) is the largest compared to other endites, but not extremly enlarged like those of Amplectobelua. The size of the endites alternates (those on even podomeres being larger than that of the odd podomere following it) and decreasing distally, except podomere 8 is larger than podomere 6 just like Amplectobelua. Compared to Amplectobelua, GLSs of Ramskoeldia are wider and three pairs of GLSs did not gradually alternated in size.[1]

Two species of Ramskoeldia had been described: Ramskoeldia platyacantha and Ramskoeldia consimilis. Endites of R. platyacantha are stout and their length did not exceeding height of podomere they attach. The shaft podomere 2 and 3 of R. platyacantha also bore prominent endites resembling those of distal articulated podomeres. While in R. consimilis, endites of distal articulated region are slender and most of them have length exceeding height of podomere they attach. The shaft of R. consimilis only have simple endite on podomere 3. Frontal appendages of R. consimilis had been misidentified as Anomalocaris saron due their similar overall appearance.[1]

References
  1. Cong, Pei-Yun; Edgecombe, Gregory D.; Daley, Allison C.; Guo, Jin; Pates, Stephen; Hou, Xian-Guang (2018). "New radiodonts with gnathobase-like structures from the Cambrian Chengjiang biota and implications for the systematics of Radiodonta". Papers in Palaeontology. 4 (4): 605–621. doi:10.1002/spp2.1219. ISSN 2056-2802.
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