New York, Sep 25 (IANS): As part of the evolutionary process, snakes may have developed courtship and male-to-male combat behaviour such as moving undulations, neck biting and spur-poking, suggests a new study.

The authors analysed 33 courtship and male-to-male combat behaviours in scientific literature by plotting them to a phylogenetic tree to identify patterns.

The authors identified the patterns in behaviour which was not always possible and then used fossil records to match the behaviour to the snakes' evolution.

Researchers found that male-to-male combat of common ancestors of the Boidae and Colubridae snake species in the Late Cretaceous were likely to have involved combatants raising the head and neck, attempting to topple each other.

"Poking with spurs may have been added in the Boidae clade. In the Lampropeltini clade, the toppling behaviour was replaced by coiling without neck-raising and body-bridging was added," said Phil Senter from the Fayetteville State University in north Carolina.

A clade is a grouping that includes a common ancestor and all the descendants (living and extinct) of that ancestor.

Snake courtship is likely to have involved rubbing with spurs in Boidae.

"In Colubroidea, courtship ancestrally involved chin-rubbing and head- or body-jerking," they added.

Various colubroid clades subsequently added other behaviour like moving undulations in Natricinae and Lampropeltini, coital neck biting in the Eurasian ratsnake clade and tail quivering in Pantherophis.

"Although many gaps in the evolution of courtship and combat in snakes remain, this study provides a first step in reconstructing the evolution of these behaviour in snakes," Senter concluded in a paper that appeared in the open-access journal PLOS ONE.