Overview
- A study published September 10, 2026, used X‑ray computed tomography on the Field Museum’s holotype of Pseudocerastes urarachnoides and found the tail vertebrae were “bizarrely normal” while the spider‑like tip is produced by modified, likely keratinous, scales.
- The specimen was first collected in 1968 and long thought to be deformed until a second specimen in 2003 led to the species’ formal description in 2006 and its designation as the holotype used in the new scans.
- Field observations and video recordings from earlier fieldwork show the tail functions as a decoy in caudal luring, with the snake wiggling the spider‑like tip to attract and ambush birds.
- Researchers credit the Field Museum’s recent XCT facility for enabling non‑destructive 3D imaging and say the international team led by Sara Ruane and Georgios Georgalis will follow up with genetic and population studies to measure gene flow and range structure.
- The findings underline a paleontological problem: isolated vertebrae in the fossil record would not reveal this extreme external adaptation, and the work strengthens the research value of museum collections for both evolutionary study and conservation planning in western Iran.