Reconstructing the cretaceous with bones and amber

A double window into the past

Post by Dr Ricardo Pérez-de la Fuente, Deputy Head of Research

Nature is wonderfully imperfect, and the data that we can gather from it is even further from perfection. Fossil localities, even those providing exceptionally well-preserved fossils, are inaccurate records of the past. Fossils can form from a variety of matter including organisms, their remains, or even traces of their activity. Yet not all of the material that can get fossilised at a particular site actually will. Among other factors, biases in the fossil record result from the nature of the materials responsible for fossilisation – usually sediments which are in the process of turning into rocks. In most cases, fossil localities offer us only a single ‘window of preservation’ – a skewed geological record of the ancient ecosystem that once existed there.

In 2012, a rich vertebrate bone bed was documented at the Ariño site in Teruel, Spain. Since then, researchers have unearthed more than 10,000 individual fossil bones, from which they have discovered new species of dinosaurs, crocodiles, and turtles. Plant fossils were also found, including pollen grains and amber, which is fossilised resin. Although amber was known to occur in this locality, this sort of material had remained unstudied… until recently.

Over the summer of 2019, I joined my colleagues to carry out amber excavations in the Ariño site – an open-pit coal mine that has an almost lunar appearance due to the dark carbonate-rich mudstone rocks and the total lack of vegetation. The scorching heat during a very hot summer was a bit maddening, but I did try to enjoy my yearly dose of sun before returning to the UK!

Resin pieces can be transported significant distances by runoff water before depositing on their final burial location, where they slowly transform into amber. However, we found amber pieces that had not moved from their original place of production. These large, round-shaped pieces preserved delicate surface patterns that would have been polished away even by the slightest transport. The resin that produced these amber pieces was formed by the roots of the resin-producing trees, and resembles sub-fossil resin my colleagues found in modern forests from New Zealand.

Large amber piece produced by roots (left) and assemblage of smaller amber pieces (right) from Ariño (Teurel, Spain).
Large amber piece produced by roots (left) and assemblage of smaller amber pieces (right) from Ariño (Teurel, Spain).

The small amber pieces from Ariño contain an unusual abundance of fossils. These pieces come from resin produced by the branches and trunk of the resin-producing trees. From the almost one kilogram of amber we excavated, we identified a total of 166 fossils. These include diverse insects such as lacewings, beetles, or wasps, and arachnids such as spiders and mites. Even a mammal hair strand was found!1

We now know that the Ariño site provides two complementary windows of preservation — a bone bed preserving a rich variety of vertebrate animals, and amber with abundant inclusions. Aside from Ariño, only three localities that preserve both dinosaur bone beds and fossiliferous amber have been reported in Western France, Western Canada, and North Central United States. However, in these cases, either the bone bed or the amber have offered a much more modest abundance and diversity of fossils. Some of the fossils from these localities also show signs of significant transport, which means that the organisms could have inhabited different, distant areas even though they fossilised together. This makes Ariño unique because it offers two valuable ‘windows of preservation’ from the same ecosystem.

Thanks to all this evidence and other data, we have been able to reconstruct an ancient terrestrial ecosystem – a 110-million-year-old coastal swamp – with unprecedented detail and accuracy.2 The inherent incompleteness of the fossil record will always remain a headache for palaeontologists… but localities like Ariño make the data that we can recover from the past a bit more complete.

Reconstruction of the coastal swamp forest of Ariño, in the Iberian Peninsula, from 110 million years ago. Author: José Antonio Peñas. Source: Álvarez-Parra et al. 2021.
Reconstruction of the coastal swamp forest of Ariño, in the Iberian Peninsula, from 110 million years ago. Author: José Antonio Peñas. Source: Álvarez-Parra et al. 2021.

If you want to learn more about amber excavations, check out this post on Excavating Amber.

1Álvarez-Parra, Sergio, Ricardo Pérez-de la Fuente, Enrique Peñalver, Eduardo Barrón, Luis Alcalá, Jordi Pérez-Cano, Carles Martín-Closas et al. “Dinosaur bonebed amber from an original swamp forest soil.” Elife 10 (2021): e72477.

2Álvarez-Parra, Sergio, Xavier Delclòs, Mónica M. Solórzano-Kraemer, Luis Alcalá, and Enrique Peñalver. “Cretaceous amniote integuments recorded through a taphonomic process unique to resins.” Scientific reports 10, no. 1 (2020): 1-12.

Uncovering ancient threads

By Dr. Frankie Dunn, Research Fellow

Some of the very oldest complex, macroscopic communities on Earth appear in the fossil record about 570 million years ago and record the presence of a group of organisms – the rangeomorphs – with an unfamiliar body plan that, at their ultimate extinction, was lost from life’s repertoire.

Rangeomorphs are characterised by a strange frondose branching anatomy, where large primary branches host smaller branches which themselves host smaller branches again. This arrangement appears to maximise the surface-area to volume ratio of the organism, rather like a lung or a gill would today.

The smallest known rangeomorphs are less than a centimetre in length, but they grew huge and the largest records indicate they could stand more than two metres tall. There is no evidence to suggest that rangeomorphs were able to move around, rather, they lived stuck to the sea floor in the deep ocean, far below the reach of light.

Despite this strange set of characters, there is growing consensus that rangeomorphs likely represent very ancient records of animal life. However, they lived at such a remote time in Earth’s history that they do not possess any direct living descendants. Given all this, it may not be a surprise to hear that we know relatively little about how these organisms made their living and came to dominate the ancient seafloors.

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The UNESCO world heritage site Mistaken Point in Newfoundland, Canada, is one of the sites on which we find exceptionally preserved rangeomorph fossils. Photo: Alex Liu.

In order to better understand them, my co-author Alex Liu and I travelled to Newfoundland, Canada to explore the rocks which host these remarkable fossils and over the past few years we have made an unexpected discovery. We found that fine filamentous threads connect rangeomorph fronds of the same species, in some cases over many meters, though they are typically between two and 40 centimetres long.

An undescribed rangeomorph fossil with filamentous connections at the base of the frond. We find that this species of rangeomorph can be connected to each other over meters! Photo: Alex Liu. 

It is possible that these filaments were involved in clonal reproduction, like strawberry plants today, but they may have had additional functions such as sharing nutrients or providing stability in strong ocean currents.

The discovery of the filaments means that we have to reconsider how we define an individual rangeomorph, and may help us understand how rangeomorphs (seemingly) rapidly colonised deep-sea environments. Either way, some reassessment of the palaeobiology of these unique organisms is certainly required!

More information:

  • Read the full research paper here.


Top image: Beothukis plumosa, a rangeomorph from Newfoundland showing the intricate branching anatomy of rangeomorphs. Photo: Alex Liu.

The crucial cortex

Lance Millar_Developmental Anatomy_14Oct2017.jpg-large

University of Oxford PhD student Lance Millar recently ran one of our Brain Spotlight events as part of the Brain Diaries exhibition programme. Here, Lance explains his research into neurodevelopmental disorders and possible treatments.

The brain has always been a fascinating organ for me. It is the site of our intelligence, our problem-solving and social skills, and it allows us to connect our senses to the world around us.

The large, folded outer part of the human brain is called the cortex, and is responsible for decision-making, language, face recognition, and a lot of the other things that I like to think are what make us human. The word cortex comes from the Greek for husk or outer shell, which underestimates the importance of what the cortex does.

Humans can survive with damage to the cortex, but depending on the part of the cortex that is damaged, a range of disabilities can result. People who have had a stroke can lose part of their cortex, leading to limb paralysis, loss of speech, or loss of memory, depending on the site of the damage.

B0009564 Human brain, coronal section, LM
Cerebral cortex – Professor Michael R Peres – Wellcome Images

Some people are also born with a developmental problem in the cortex, and are said to have a neurodevelopmental disorder. Such conditions are thought to include autism, schizophrenia, ADHD, and even dyslexia – all fairly common conditions. The damage to the cortex is subtle and complex in these conditions, and scientists are still working out exactly what happens to the brain during its prenatal development.

I am studying one particular neurodevelopmental disorder caused by lack of oxygen at birth. It is known to medical specialists as neonatal hypoxia ischaemia. The image on the right shows a cross-section MRI scan of a normal newborn human brain, alongside some babies who have been damaged by oxygen deprivation. You can see that the brains are smaller, the cortex is less folded and it takes up less space inside the skull.

MRI scans of normal newborn brains alongside those of babies who have been damaged by oxygen deprivation. Image: Woodward et al., New England Journal of Medicine, 2006

Scientists still don’t know how to protect the newborn brain from these injuries. Some are caused by inflammation which is a normal response to illness, but can wreak havoc in the confined space of the skull. Some is caused by the presence of free radicals, which are thought to contribute to ageing and organ failure, as the newborn brain doesn’t have many antioxidants to fight these chemicals. It’s also possible that the electrical signals that neurons within the brain send to each other contribute to the damage when there isn’t enough oxygen to feed them.

So what can we do to treat oxygen deprivation at birth? One breakthrough treatment currently available is known known as hypothermia. In this technique, the baby is cooled to 33℃ which slows down the brain-damaging chemical reactions which in turn protects the brain. This is currently the only treatment available, but I am involved in the study of possible alternatives.

We don’t want to introduce any drugs to the baby’s system as they might be harmful to normal development. So scientists are currently working on treatments which help the baby’s natural body proteins to protect the brain. I do this by looking at neurons under the microscope, and identifying proteins expressed by these neurons using fluorescent probes known as antibodies.

Neurons under the microscope
An example of neurons under the microscope. Image: Lancelot Millar

These neurons are expressing neuroserpin, a natural brain protein which decreases inflammation and cell death. I’m looking at exactly where neuroserpin is expressed in the brain, how it can be upregulated in response to oxygen deprivation, and how its chemical reactions could be used to protect the brain.

Another way to help people with neurodevelopmental disorders is to better understand how the cortex connects to other parts of the brain and how it can carry out complicated decisions. There is still so much to understand about the complexity of the human brain, and what seems like fundamental research could generate the springboard for new ideas for neurodevelopmental disorder treatments.

To explore the structure of the human brain and compare it to that of other animals see the Brain Diaries Brain Explorer below.


The Big Brain Competition

What happens in your brain when you receive compliments? And what’s going on in your mind when you watch your football team win a match? Does the brain respond differently when recalling music, compared to listening to it? All these questions, and more, have been posed in our Big Brain Competition

Coinciding with the Museum’s Brain Diaries exhibition, the Wellcome Centre for Integrative Neuroimaging is inviting you to ask your own question about the brain to be in with a chance to have it tested by neuroscientists using Oxford’s state-of-the art Magnetic Resonance Imaging (MRI) scanner.

The advanced MRI scanner at the John Radcliffe Hospital in Oxford is one of the strongest in the world. It allows scientists to carry out functional MRI (fMRI) scans to see the brain in action. This mind-blowing procedure can reveal how the brain changes when learning a new skill or how it compensates when someone recovers from brain damage. It can also reveal which areas are used when people speak, move or laugh, to give just a few examples.

This fMRI scan shows how blood flows to the visual cortex region at the back of the brain when viewing a visually-stimulating checkerboard pattern

Dr Stuart Clare of the Nuffield Department of Clinical Neurosciences is asking you for questions about the brain

Functional MRI shows when a brain area is more active by detecting the changes in blood oxygen levels and blood flow that happen in response to neural activity. The technique can be used to produce activation maps showing which parts of the brain are involved in a particular mental process.

The scientist behind the Big Brain Competition is Dr Stuart Clare, whose research involves pushing the technological boundaries of the fMRI technique to reveal new insights about how the brain functions normally and how it is affected by disease. There is still so much that the fMRI scans can bring to light, so Stuart is asking you for ideas!

Over several years of inviting people in to see the beautiful pictures that our MRI scanner can produce, I’ve been fascinated by the questions they have about the brain and whether you can see this thing or that thing in our fMRI scans.  With this competition we want to give people the unique access to our scanner and the chance to try an idea out for themselves.

When coming up with an idea for investigation there are a few practical things to bear in mind. Any activity has to be something people can do when lying down in the scanner and it has to be clear when they start and stop doing the activity. But Stuart is very open to ideas for experiments that they haven’t come across before – something that scientists really don’t already know the answer to.

The animation below explains how fMRI works and what it can do. So take a look, think up an experiment of your own and enter your idea via this form. The best one will be put into action by the research team and you will be able to watch the scans take place at the John Radcliffe Hospital yourself!