Research Changes Views over Evolution of Jawed Vertebrates

An international team of scientists, including researchers from Manchester University, have helped unravel the secrets hidden in the fossilised remains of an ancient hagfish, a slimy, eel-like fish whose descendants still swim the oceans of the world today.

Working in collaboration with researchers from the University of Chicago (Illinois, USA), the Manchester University team have identified the first detailed fossil of a hagfish.  The Manchester team were led by Professors Phil Manning and Roy Wogelius, powerful X-rays were used to provide a detailed examination of the fossil specimen, providing a fresh perspective on the evolution of jaws in animals with back bones (vertebrates).

The Tethymyxine tapirostrum fossil Specimen Being Prepared for Synchrotron Analysis

Tethymyxine tapirostrum fossil.

Tethymyxine tapirostrum fossil being prepared for synchrotron X-ray analysis.

Picture Credit: University of Manchester

The X-rays were produced using the Stanford Synchrotron Radiation Lightsource (SSRL), a cyclic particle accelerator at Stanford University (California).  Once the fossil had been scanned, the data produced helped answer the question as to when these ancient jawless fish branched-off the vertebrate evolutionary tree.

An Important Discovery

The discovery is incredibly important as it changes our view of the evolutionary lineage that gave rise to modern-day jawed vertebrates (gnathostomes), from bony fish to humans.  The scientific paper is being published in the “Proceedings of the National Academy of Sciences”.  The fossil, a specimen of a hagfish from the Late Cretaceous comes from Lebanon and it measures just over thirty centimetres long.  The fossil represents a species named Tethymyxine tapirostrum.

Commenting on the importance of this research, Professor Phil Manning (Chair of Natural History at the University of Manchester) stated:

“This is an extremely significant discovery as it recalibrates our understanding of the evolutionary history of all early vertebrates, an ancestral line that leads to all jawed beasties including us. Humans!”

Professor Manning added:

“This wonderful fossil plugs a 100-million-year gap in the fossil record and shows that hagfish are more closely related to the lamprey than to other fishes.  The chemical maps produced at SSRL enabled our team to see for the first time the anatomical features so crucial to the interpretation of this very distant relative.”

Lampreys are another form of ancient, blood-sucking, jawless fish also still in existence today.  These findings show that both the hagfish and lamprey evolved their eel-like body form and strange feeding systems after they branched off from the rest of the vertebrate line of ancestry about 500 million years ago, during the Cambrian geological period.

Professor Manning at the SSRL (Stanford University)

Professor Phil Manning at the Stanford Synchrotron Radiation Lightsource (SSRL).

Professor Manning at the Stanford Synchrotron Radiation Lightsource (SSRL).

Picture Credit: University of Manchester

Dr Tetsuto Miyashita, (Fellow in the Department of Organismal Biology and Anatomy at Chicago University), who led the research, explained:

“This is a major reorganisation of the family tree of all fish and their descendants.  This allows us to put an evolutionary date on unique traits that set hagfish apart from all other animals.”

The Bizarre Hagfish

The bizarre hagfish are entirely marine and are the only known living animals that possess a rudimentary skull but no vertebral column.  They do have very primitive vertebrae but instead of a back bone like other vertebrates they just have a modified notochord.  They have a unique defence mechanism to help them ward off ocean predators such as sharks.  They can produce copious amounts of slime, clouding the water in their proximity and clogging the gills of would-be attackers.  In some parts of Asia, such as South Korea, this slime is prized and used in cooking.

It was this ability to produce slime that made the Tethymyxine fossil all the more important and rare.  The discrete chemistry locked within the fossil could only be mapped using synchrotron-based imaging techniques developed by the Manchester/SSRL team.  Manchester University  is an established world leader in the synchrotron-based imaging of fossil remains.  This technique has permitted the team to identify the “chemical ghost” of the preserved soft tissue and slime glands of the fossil.  Soft tissues are rarely preserved as fossils, which is why there are so few examples of prehistoric hagfish for palaeontologists to study.

The detailed scans picked up the chemical signal for keratin, the same material that makes up your hair and nails.  Keratin is a crucial part of what makes the hagfish slime defence so effective.

Professor Wogelius, (Chair of Geochemistry at The University of Manchester), commented:

“Our team at Manchester has been using these increasingly sophisticated imaging techniques to help us better understand ancient fossils and resolve chemistry derived from both the organism and the environment in which they were preserved.”

Professor Manning added:

“This ‘chemical’ fossil has offered new and exciting evidence that has enabled a more robust reconstruction of the vertebrate family tree.  However, it was only made possible through the collaboration of an international team, as Darwin once said, ‘In the long history of humankind (and animal kind, too) those who learned to collaborate and improvise most effectively have prevailed’”.

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