Modern-looking lampreys ‘older’ than thought
Posted on homepage: 14 February 2008 (GMT+10)
It had been assumed up until the late twentieth century that cyclostomes, living jawless vertebrates that include the lamprey and hagfish, evolved from armoured jawless vertebrates that supposedly lived from the Ordovician to the Devonian periods, 490 to 358 Ma within the evolutionary/uniformitarian timescale.1 Furthermore, lampreys and hagfish were supposed to have diverged from a common ancestor sometime in the early Mesozoic about 250 Ma.2 Then lampreys and hagfish were discovered in ‘older’ rocks from the Carboniferous period.
Just recently a lamprey was discovered from the late Devonian period, considered 360 Ma.3 This discovery pushes back the oldest dates for lampreys by about 35 Ma. The most amazing aspect of the new fossil is that it looks surprisingly modern, indicating little or no change in lampreys for 360 Ma! Janvier is astonished:
‘This shows that lamprey morphology has been astonishingly stable for 360 Myr, and proves that lampreys and hagfishes had already diverged by late Devonian times, earlier than previously thought.’
Furthermore, DNA and RNA sequence data supposedly shows that lampreys and hagfish are ‘sister groups’, while morphological and physiological aspects tell researchers that they evolved from different groups. Their evolution now is thought to have occurred before the armored jawless vertebrates.4 So, there is much confusion over the supposed evolution of cyclostomes.
Not only does the new discovery push back the supposed evolution of both lampreys and hagfish, but also shows little change in all that time. Maybe, the fossil record is trying to tell us that hagfish, lampreys and various armoured, extinct fish are independent creations.
- Janvier, P., Modern look for ancient lamprey, Nature 443:921–924, 2006; p. 921. Return to text.
- Janvier, ref. 1, p. 923. Return to text.
- Gess, R.W., Coates, M.I. and Rubidge, B.S., A lamprey from the Devonian period of South Africa, Nature 443:981–984, 2006. Return to text.
- Janvier, ref. 1, p. 924. Return to text.