Why are we interested in tetrapods from the early Carboniferous?
Tetrapods are the first vertebrate animals to walk on the land, and are our long-long-distant ancestors. The earliest tetrapods evolved from fish, when fish fins developed to become weight supporting, walking limbs, then they developed lungs and probably lived like amphibians today, before fully-terrestrial reptile-like animals evolved. The early Carboniferous period (from 360 million years ago for the next 20 million years) is historically known for its scarcity of tetrapod fossils (the period is often referred to as Romer’s Gap). New fossils from Scotland and the Borders region are starting to fill in some of the gaps and uncover some of the missing links in tetrapod evolution.
Who are TWEED?
The TWEED project involves 12 scientists from across the UK, funded by the Natural Environment Research Council. The consortium is lead by Prof. Jenny Clack (University Museum of Zoology, Cambridge) and involves the Universities of Leicester, Cambridge and Southampton, the British Geological Survey and the National Museum of Scotland.
The TWEED team meeting at the University Museum of Zoology, Cambridge at the start of the project.
Photo of me in the Department of Geology, Leicester. Jane the T-Rex wanted to be in the photo too.
The exciting thing about the project for me is that we will not just study the tetrapod fossils themselves, but all the other fossils they are found with, the sediment types and geochemical signatures. For the fossils this includes fish, arthropods (such as giant millipedes), plants, microfossils and more. And the sediments can tell us what the environment was like, such as a beach, lake or swamp. This is why it is a real team effort, as we will use every different sort of evidence to really understand what happened and why in the tetrapod world.
At the University of Leicester colleagues and I are studying the ancient environment in which the tetrapods lived (the palaeoenvironment) from the type of sediments they are found in, and their geochemistry (rock and fossil chemistry) to interpret what the climate was like at the time they lived (the palaeoclimate). With the team we will look at many different rock exposures containing tetrapods and match them up (correlate them) into a time frame. To do this we will examine microfossils such as plant spores and ostracods that can give an indication of time and environment.
This is one of my favourite rocks from the early Carboniferous of the Borders. It is a sandstone made up of layers of ripples that are stacked up together, telling a story of an ancient river or estuary channel.
Sometimes the rocks are very hard to see, especially along the coast line where they are only present below the tide line. Here is Researcher Janet Sherwin from the University of Leicester standing by some very barnacle-covered rock!
There will be some very exciting science in the months and years to come, and I will update you with live ‘science as it happens’ blogs, such as when we will drill a 500 metre deep borehole and find fantastic new fossil discoveries. During quieter times I hope to entertain you with some posts on How Science Works, Fossil Fact Files and Team Member Profiles. Please do post any comments or email me at email@example.com, as I would love your feedback and to answer your questions.
We will soon have a website for the TWEED project hosted by the British Geological Survey, so I will let you know when this is up and running.
Wow! of the week
My wow! moment this week came when I found my first vertebrate bone and ostracod fossils, in the same rock! The bone and the ostracods were very small (1mm size), but visible under a microscope. The bone may be fish or tetrapod in origin, the pieces are a little small to identify. The ostracods are small arthropod crustaceans (they are my favourite fossil) and present in their hundreds! The occurrence of both of these fossils together is great news as it gives us more clues to fill in the puzzle – ostracods are very picky about where they live and different species are adapted to different conditions such as salinity. I will be looking out for more discoveries like this as I work.
Until next timeCarys