Scientists Take First Measurements Of The Radiation Dose On The Lunar Surface (Planetary Science)

Using the Lunar Lander Neutrons and Dosimetry (LND) experiment aboard China’s Chang’E 4 lander, a team of researchers from Germany and China has measured an average dose equivalent of 1,369 μSv/day on the surface of the Moon.

View of the Chang’E 4 lander with the location of the LND sensor head indicated by the red arrow. LND is mounted in the Chang’E 4 payload compartment; the lid at the tip of the red arrow is closed at night to protect LND from the cold lunar night. Image credit: Chinese National Space Agency / National Astronomical Observatories of China.

The Moon is the next stepping stone for human space exploration, and several nations have announced plans for its exploration by humans.

Space radiation exposure is one of the major risks for astronauts’ health as the chronic exposure to galactic cosmic rays may have late health effects such as induction of cataract, cancer, or degenerative diseases of the central nervous system or other organ systems.

It appears that there have been no active measurements of the radiation dose rate on the lunar surface until China’s Chang’E 4 mission landed in the von Karman crater on the far side of the Moon in January 2019.

During the Apollo missions, astronauts carried dosimeters with them to the Moon, but the radiation data from the surface of the Moon were never reported.

“Over the coming years and decades, various nations are planning to send crewed missions to explore the Moon. Space radiation poses a significant risk to the health of humans,” said LND project manager Dr. Oliver Angerer, a researcher in the Space Administration at the German Aerospace Center (DLR).

“The Apollo astronauts carried radiation measuring devices, referred to as dosimeters, on their bodies. But these only determined the radiation exposure over the course of the entire mission.”

“The radiation exposure we have measured is a good benchmark for the radiation within an astronaut suit,” added co-author Dr. Thomas Berger, a researcher at the German Aerospace Center (DLR).

The LND instrument measured an average dose equivalent of 1,369 μSv/day on the lunar surface.

For the same time period, the dose equivalent onboard the International Space Station (ISS) was 731 μSv/day with contributions only from galactic cosmic rays of 523 μSv/day. The additional 208 μSv/day is due to protons while crossing the South Atlantic Anomaly.

Therefore, the daily galactic cosmic ray dose equivalent on the surface of the Moon is around a factor of 2.6 higher than the dose inside the ISS.

“The measurements show an equivalent dose rate of about 60 μSv per hour,” said co-author Dr. Robert Wimmer-Schweingruber, a scientist at Kiel University.

“In comparison, on a long-haul flight from Frankfurt to New York, it is about 5 to 10 times lower, and on the ground well over 200 times lower.”

“Since astronauts would be on the Moon for much longer than passengers flying to New York and back, this represents considerable exposure for humans.”

“During long-term stays on the Moon, the astronauts’ risk of getting cancer and other diseases could thus be reduced,” said DLR researcher Dr. Christine Hellweg, co-author of the study.

References: Shenyi Zhang et al. 2020. First measurements of the radiation dose on the lunar surface. Science Advances 6 (39): eaaz1334; doi: 10.1126/sciadv.aaz1334 link: https://advances.sciencemag.org/content/6/39/eaaz1334

First Fossil Feather Ever Found Belonged to Archaeopteryx (Paleontology)

Renowned as the first fossil feather ever known, the 150-million-year-old isolated fossil feather found in the Jurassic limestone deposits of Solnhofen, Germany, in 1861 is an upper major primary covert of Archaeopteryx, according to new research.

Left: optical photograph of the 150-million-year-old isolated fossil feather of Archaeopteryx. Scale bar – 5 mm. Upper right: the Berlin skeletal specimen of Archaeopteryx. Scale bar – 5 cm. Bottom right: a wing of Archaeopteryx; black represents upper major primary coverts (UMPCs), dark gray represents primaries, and light gray represents secondaries and upper major secondary coverts. Image credit: Carney et al, doi: 10.1038/s41598-020-65336-y / 10.1038/ncomms1642.

Dr. Ryan Carney from the University of South Florida and his colleagues analyzed nine attributes of the 150-million-year-old feather, particularly the long quill, along with data from modern birds.

The researchers also examined the 13 known skeletal fossils of Archaeopteryx, three of which contain well-preserved primary coverts.

They found that the top surface of an Archaeopteryx wing has primary coverts that are identical to the isolated feather in size and shape.

The isolated feather was also from the same fossil site as four skeletons of Archaeopteryx, confirming their findings.

“There’s been debate for the past 159 years as to whether or not this feather belongs to the same species as the Archaeopteryx skeletons, as well as where on the body it came from and its original color,” Dr. Carney said.

“Through scientific detective work that combined new techniques with old fossils and literature, we were able to finally solve these centuries-old mysteries.”

Using a specialized type of electron microscope, the scientists determined that the feather came from the left wing of Archaeopteryx.

They also detected melanosomes, which are microscopic pigment structures.

After refining their color reconstruction, they found that the feather was entirely matte black.

“We provide additional insights, such as an updated color reconstruction of the entire feather as matte black, with 90% probability,” the authors said.

“Given the isolated nature of the fossil feather, we can never know the anatomical and taxonomic provenance with 100% certainty.”

“However, based on all available anatomical and taxonomic evidence, independently confirmed by close morphological connections to multiple skeletal specimens, the most empirical and parsimonious conclusion is that the isolated feather represents a primary covert of Archaeopteryx.”

References: R.M. Carney et al. 2020. Evidence corroborates identity of isolated fossil feather as a wing covert of Archaeopteryx. Sci Rep 10, 15593; doi: 10.1038/s41598-020-65336-y

Evidence Of Stellar Explosion Found In Earth’s Proximity (Astronomy)

Discovery of iron-60 and manganese-53 substantiates supernova 2.5 million years ago

When the brightness of the star Betelgeuse dropped dramatically a few months ago, some observers suspected an impending supernova – a stellar explosion that could also cause damage on Earth. While Betelgeuse has returned to normal, physicists from the Technical University of Munich (TUM) have found evidence of a supernova that exploded near the Earth around 2.5 million years ago.

This manganese crust started to grow about 20 million years ago. It grew layer by layer until it was retrieved a few years ago and analyzed in the Maier-Leibnitz-Laboratory at the Technical University of Munich. In layers that are around 2.5 million years old, the researchers found iron-60 and elevated levels of manganese-53. Their occurrence is evidence of a near-Earth supernova 2.5 million years ago. Credit: Dominik Koll / TUM

The life of stars with a mass more than ten times that of our sun ends in a supernova, a colossal stellar explosion. This explosion leads to the formation of iron, manganese and other heavy elements.

In layers of a manganese crust that are around two and a half million years old a research team led by physicists from the Technical University of Munich has now confirmed the existence of both iron-60 and manganese-53.

“The increased concentrations of manganese-53 can be taken as the “smoking gun” – the ultimate proof that this supernova really did take place,” says first author Dr. Gunther Korschinek.

While a very close supernova could inflict massive harm to life on Earth, this one was far enough away. It only caused a boost in cosmic rays over several thousand years. “However, this can lead to increased cloud formation,” says co-author Dr. Thomas Faestermann. “Perhaps there is a link to the Pleistocene epoch, the period of the Ice Ages, which began 2.6 million years ago.”

Ultra-trace analysis

Typically, manganese occurs on earth as manganese-55. Manganese-53, on the other hand, usually stems from cosmic dust, like that found in the asteroid belt of our solar system. This dust rains down onto the earth continuously; but only rarely do we perceive larger specks of dust that glow as meteorites.

New sediment layers that accumulate year for year on the sea floor preserve the distribution of the elements in manganese crusts and sediment samples. Using accelerator mass spectrometry, the team of scientists has now detected both iron-60 and increased levels of manganese-53 in layers that were deposited about two and a half million years ago.

“This is investigative ultra-trace analysis,” says Korschinek. “We are talking about merely a few atoms here. But accelerator mass spectrometry is so sensitive that it even allows us to calculate from our measurements that the star that exploded must have had around 11 to 25 times the size of the sun.”

The researchers were also able to determine the half-life of manganese-53 from comparisons to other nuclides and the age of the samples. The result: 3.7 million years. To date, there has only been a single measurement to this end worldwide.

References: G. Korschinek, T. Faestermann, M. Poutivtsev, A. Arazi, K. Knie, G. Rugel, and A. Wallner Supernova-Produced 53Mn on Earth Physical Review Letters, 125, 031101, July 17, 2020 – DOI: 10.1103/PhysRevLett.125.031101

Provided by Technical University Munich

Scientists Synthesise a Material Capable Of Degrading Nerve Agents In Water (Material Science)

A team from the Institute of Molecular Science (ICMol) of the University of Valencia has succeeded in synthesizing a new porous material that enables and guides the degradation of compounds analogous to nerve agents used in chemical warfare. This material will make it possible to capture and degrade this type of compounds that until now could not be eliminated. The work has been published in magazine Chem.

Nerve agents are highly toxic chemicals that poison the body’s central nervous system and prevent it from working properly. They act quickly and their effects range from dizziness to death in the most extreme cases. An example of these agents is Sarin, a synthetic compound classified as a weapon of mass destruction and used in terrorist attacks such as the Tokyo subway in 1995 or, more recently, the 2013 Ghouta massacre in the framework of the Syrian War. Currently, the reference material to capture these gases is activated carbon, which allows them to be retained, but not eliminated.

The ICMol team led by Carlos Martí-Gastaldo, FuniMAT, works with porous materials called MOFs (Metal-Organic Frameworks) whose versatility makes it possible to create design materials by modifying their properties. In this way, they have succeeded in synthesizing a new family of highly efficient and chemically stable MOFs (MUV-101) that are capable of degrading a Sarin gas analogue in a way that is very similar to enzymes, the biological catalysts par excellence. “On a laboratory scale, we use nerve agent analogues to avoid the problems derived from their obvious toxicity. That is why we are working with foreign defense agencies to certify that this degradation can be extrapolated to Sarin gas itself,” explains Martí-Gastaldo.

The stability and efficiency of these designed molecular buildings has been achieved thanks to the incorporation of titanium and iron in their structure. The study published in magazine Chem shows that both metals together have a much higher activity than they would have separately, thus achieving a cooperative catalysis that enables an efficient degradation of the nerve agent in water, without the need for any specific or additive medium for the reaction to take place.

These new materials, partially created and developed by Javier Castells, Natalia M. Padial, Neyvis Almora, María Romero and Sergio Tatay, have already been patented and can easily be integrated into protective suits or gas masks. For this reason, they can be of great interest in security matters, both in the defense of countries against threats of chemical warfare, and the environment, as well as for personal protection against strong insecticides or the decontamination of waters.

References: Javier Castells-Gil et al. Heterometallic Titanium-Organic Frameworks as Dual-Metal Catalysts for Synergistic Non-buffered Hydrolysis of Nerve Agent Simulants, Chem (2020). DOI: 10.1016/j.chempr.2020.09.002 link: https://linkinghub.elsevier.com/retrieve/pii/S2451929420304666

Provided by Asociacion RUVID

New Discovery Helps Researchers Rethink Organoid Cultures (Medicine)

Organoids are stem cell-based tissue surrogates that can mimic the structure and function of organs, and they have become a key component of numerous types of medical research in recent years. But researchers from The University of Texas at Austin have uncovered problems with the conventional method for growing organoids for common experiments that may cause misleading results.

A look at an organoid sample, with different sizes based on their location in the culture. Credit: University of Texas at Austin

The researchers discovered that the size of organoids differ depending on where they are located within the hydrogel material called extracellular matrix (ECM) that is commonly used in biomedical research. The team found that organoids on the edges of a dome-shaped ECM respond differently to chemical or biological stimuli compared to those in the center of the dome.

This observation means one organoid in the core might react positively to a new treatment or drug, while another one on the edge could have a negative reaction, potentially muddying the results of an experiment. Ideally, organoids would be consistent in size and reaction in preclinical experiments.

“There are hundreds of organoids in the hydrogel dome, and they’re showing different sizes, different functions, and that can be problematic” said Woojung Shin, a postdoctoral fellow and recent Ph.D. graduate from the Cockrell School of Engineering’s Department of Biomedical Engineering, who discovered the problem. “You may get very different results from what would actually happen in the human body as a result.”

The findings were published recently in Cell Press’ iScience. The team includes researchers from the Biomimetic Microengineering Laboratory in the Cockrell School and the Livestrong Cancer Institutes of UT’s Dell Medical School.

The research began when Shin noticed that something felt off while examining organoids. They were slightly different sizes based on their location in the sample.

They repeated the experiment and identified the same issues time after time with different organoid lines. The team found morphogens in the culture medium — signaling molecules that are essential for organoid growth — that can spread and create a “gradient” within the hydrogel domes. One of the representative morphogens, Wnt3a, was extremely unstable. A computational simulation confirmed that the size difference in organoids is likely explained by the morphogen gradient and its instability.

The paper mainly focuses on the problem the researchers uncovered, but it also offers a roadmap for finding solutions. The key, the researchers say, is to stabilize the Wnt3a protein across the sample, reducing the size of the gradient created and, subsequently, the location-based differences in the organoids.

Woojung Shin, a postdoctoral fellow and recent Ph.D. graduate from the Cockrell School of Engineering’s Department of Biomedical Engineering and biomedical engineering assistant professor Hyun Jung Kim. Credit: The University of Texas at Austin

Shin is a member of biomedical engineering assistant professor Hyun Jung Kim’s research group. She focuses on disease modeling and bioinspired organ mimicry.

Organoids are an important part of the ongoing research conducted by Kim and his group. The team uses nature’s engineering principles, or biomimetic engineering, to solve the fundamental questions about human health and disease, most notably through its organ-on-a-chip technology.

Continuing to refine organoid research principles is key to the success of Kim’s group as well as a host of different types of medical research. The paper mentions disease modeling, tissue engineering, patient-specific validation of new drug candidates and research into the relationship between demographics and disease as areas that have benefitted from organoid research.

“We really want to have reproducible and reliable experimental results,” Kim said. “What we’ve found here is that we all need to be more cautious about how we interpret data, and then maybe we can decrease the risk of misinterpretation.”

References: Woojung Shin et al, Spatiotemporal Gradient and Instability of Wnt Induce Heterogeneous Growth and Differentiation of Human Intestinal Organoids, iScience (2020). DOI: 10.1016/j.isci.2020.101372 link: https://www.cell.com/iscience/fulltext/S2589-0042(20)30560-5?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS2589004220305605%3Fshowall%3Dtrue

Provided by University of Texas at Austin

New Research Sheds Light On Why Tumour Cells Become Resistant To Chemotherapy (Oncology / Medicine)

A team of University of Alberta researchers has identified a new mechanism through which tumour cells become resistant to chemotherapy—a discovery that could lead to better treatments for women with breast cancer.

U of A researchers have shed new light on how tumour cells develop resistance to chemotherapy—a discovery that could lead to better treatments for women with breast cancer. (Photo: Getty Images)

Michael Jewer, a post-doctoral researcher in the Faculty of Medicine & Dentistry, said that more than 20 per cent of breast cancer patients will die due to therapy resistance and metastasis, the spread of the original tumour to other parts of the body. One way therapy resistance occurs is through hypoxia, or low oxygen levels. Hypoxia can occur within a tumour because it grows much more quickly than the surrounding tissue. And because blood vessels aren’t able to grow deep into the tumour, there is an area within it that remains deprived of oxygen and nutrients. This can cause major changes in the cells, the most notable being plasticity, a characteristic that allows the tumour cells to become metastatic.

Jewer and Lynne Postovit, who recently joined the Department of Biomedical and Molecular Sciences at Queen’s University, are part of the team that turned their attention to mTOR inhibitors, a group of drugs that have been used in various ways to treat cancers. mTOR inhibitors interfere with a cellular pathway in the same way hypoxia does, so they wondered whether these drugs could do something similar to what hypoxia did within the tumour cells.

They found that mTOR inhibitors did mimic hypoxia and resulted in the production of different versions of three messenger RNAs (mRNAs), information carriers the body uses to produce proteins from our genes. These different versions are especially suited to allow protein production in stressful cancer conditions such as hypoxia and chemotherapy, and the production of proteins from them leads to tumour progression.

“By better understanding this mechanism that allows tumours to progress and become metastatic, we can potentially devise treatments to prevent it,” explained Jewer, who along with Postovit is a member of the Cancer Research Institute of Northern Alberta.

According to the researchers, when an experimental drug called ISRIB that interferes with the reprogramming of protein production—like what is happening with the three mRNAs—was administered, tumour progression was halted.

The findings have led to further questions.

One of the next steps involves looking at whether compounds such as ISRIB—a drug that has been shown to mitigate many negative effects of cancer therapy—can be used to potentially help prevent metastasis and therapy resistance.

References: Jewer, M., Lee, L., Leibovitch, M. et al. Translational control of breast cancer plasticity. Nat Commun 11, 2498 (2020). https://doi.org/10.1038/s41467-020-16352-z link: https://www.nature.com/articles/s41467-020-16352-z

Provided by University of Alberta

‘Loss Of Pleasure’ Found In Teen Sleep Study (Psychology)

Sleep patterns around the world have been disrupted as screen time increases and sleep routines change with COVID-19 self-isolation requirements.

Negative mood is not unusual in adolescence, but lack of sleep can affect mental health, causing anhedonia (or loss of pleasure), anxiety, anger and significantly increasing the risk of depression, a global study of more than 350,000 teens shows.

The results just published in Sleep Medicine Reviews connects less sleep with a 55% increased chance of mood deficits and double the risk of reduced positive mood.

From Asia, to Australia, New Zealand, Europe and North America, sleep clearly was a modifiable risk factor that can improve or depress mood in adolescents, says Flinders University sleep researcher Dr Michelle Short.

“Sleep duration significantly predicts mood deficits on all mood states, including increased depression, anxiety, anger, negative affect and reduced positive affect,” she says, with less sleep linked to an 83% higher chance or anger, 62% increased risk of depressed mood, and 41% higher risk of anxiety.

“Fortunately, there are many interventions individuals, family, the community and even public policy can encourage to maintain regular sleep in this at-risk population to reduce the likelihood of these problems spilling over into mental health issues needing clinical treatment,” she says.

The researchers also recommend increased parental / guardian regulation of sleep and technology use, delayed school starting times, and monitoring academic and other pressures such as out-of-hours tutoring does not impede sleep routine.

Dr Short says that “while positive mood doesn’t get much attention, it is still clinically relevant as one of the key symptoms of depression in anhedonia (loss of pleasure).”

“It is imperative that greater focus is given to sleep as for prevention and early intervention for mood deficits,” the study concludes.

References: Michelle A. Short, Stephen A. Booth, Omar Omar, Linda Ostlundh, Teresa Arora. The relationship between sleep duration and mood in adolescents: A systematic review and meta-analysis. Sleep Medicine Reviews, 2020; 52: 101311 DOI: 10.1016/j.smrv.2020.101311

Provided by Flinders University

Mosquitos Lost An Essential Gene With No Ill Effects (Entomology / Biology)

University of Maryland entomologists discovered that a gene critical for survival in other insects is missing in mosquitos–the gene responsible for properly arranging the insects’ segmented bodies. The researchers also found that a related gene evolved to take over the missing gene’s job. Although laboratory studies have shown that similar genes can be engineered to substitute for one another, this is the first time that scientists identified a gene that naturally evolved to perform the same critical function as a related gene long after the two genes diverged down different evolutionary paths.

This image shows the exoskeletons of a normal mosquito larva on the left and a mosquito larva with the gooseberry gene edited out on the right. Image credit: Alys Jarvela/University of Maryland.

The work emphasizes the importance of caution in genetic studies that use model animals to make conclusions across different species. It also points to a new potential avenue for research into highly targeted mosquito control strategies. The research study was published in the September 30, 2020, issue of the journal Communications Biology.

“Every single arthropod has a segmented body plan. And you would think it develops the same way in all of them. But what we found is that it doesn’t,” said Alys Jarvela, a postdoctoral associate in the UMD Department of Entomology and the lead author of the study. “We learn a lot in biology by studying a process in a model organism and assuming that it works essentially the same way, using the same genes, in other organisms. That is still an incredibly useful approach. But, now we know that there is also a possibility for gene substitutions to be made in nature.”

Jarvela discovered the missing gene in mosquitos by accident. She was studying crickets and attempting to cross-check her genetic samples by comparing the gene sequences of crickets with those of other insects. She was specifically interested in a gene called paired, one of a handful of genes that guides the pattern of repeated parts in segmented animals like insects. Laboratory studies had shown that when paired is knocked out or silenced in fruit flies, every other segment of the insect’s body fails to develop, and it doesn’t survive.

“I was just trying to find the mosquito version of paired to use as a reference point, and I couldn’t find, it,” Jarvela said.

When she searched for paired in all publicly available databases of mosquito genomes, she discovered it was missing from every mosquito species represented. “Once we accepted that the gene was really absent, we thought that was a pretty wild mystery and immediately changed gears to satisfy our curiosity,” Jarvela said.

Jarvela’s team searched the genomes of fly species closely related to mosquitos and found they all contained the paired gene. This indicated that the loss of paired is a recent evolutionary event that took place only in mosquitos. It was clear to the researchers that some other gene in mosquitos must be performing the same function as paired does in other insects.

They found clues suggesting which gene could be involved in a 1996 experiment on fruit flies. In that study, scientists knocked out paired and replaced it with a closely related gene called gooseberry, which normally has a distinct role at a later time in development. That was a highly engineered experiment, but it showed that when gooseberry was manipulated to express at the right time during development, fruit flies without the paired gene developed normal alternating segments and survived.

To find out if gooseberry had naturally evolved as a substitute for paired in mosquitos, Jarvela and her team used CRISPR to edit gooseberry out of a mosquito species called Anopheles stephensi. The mutated mosquito embryos looked like laboratory fruit fly embryos that had paired knocked out.

“This work shows that even when different species share a trait or feature, the genetic mechanisms underlying this shared trait may be different,” said Leslie Pick, professor and chair of the Department of Entomology at UMD and the study’s senior author. “In the case reported in this paper, segmentation still happens even though a gene we thought was essential is lost. Our next steps will be to search for additional examples of variation in gene regulatory networks in insects and try to determine how genetic rewiring occurs in nature.”

Jarvela is also interested in probing other aspects of mosquito development that may be affected by the loss of the paired gene. In addition to controlling segmentation, which is critical for survival, paired influences male fertility in fruit flies.

“That means different genes probably regulate male fertility in mosquitos, and they might be unique to the mosquito, which could potentially provide a powerful avenue for controlling mosquitoes without harming other insects such as butterflies and bees,” Jarvela said.

References: Cheatle Jarvela, A.M., Trelstad, C.S. & Pick, L. Regulatory gene function handoff allows essential gene loss in mosquitoes. Commun Biol 3, 540 (2020). https://doi.org/10.1038/s42003-020-01203-w link: https://www.nature.com/articles/s42003-020-01203-w

Provided by University Of Maryland

How Reptiles Divided Up The Spoils In Ancient Seas? (Paleontology)

While dinosaurs ruled the land in the Mesozoic, the oceans were filled by predators such as crocodiles and giant lizards, but also entirely extinct groups such as ichthyosaurs and plesiosaurs.

Duria Antiquior – a more ancient Dorset. Watercolour of a Mesozoic marine ecosystem by geologist Henry De la Beche, painted in 1830. Ancient oceans have fascinated natural historians since the 1800s. Credit: Tom Stubbs, University of Bristol

Now for the first time, researchers at the University of Bristol have modelled the changing ecologies of these great sea dragons.

Mesozoic oceans were unique in hosting diverse groups of fossil reptiles, many of them over 10 metres long.

These toothy monsters fed on a variety of fishes, molluscs, and even on each other. Yet most had disappeared by the end of the Cretaceous, 66 million years ago, when the dinosaurs also died out. There are still some marine crocodiles, snakes and turtles today, but sharks, seals, and whales took over these ecological roles.

In a new study, completed when she was studying for the MSc in Palaeobiology at the University of Bristol’s School of Earth Sciences, Jane Reeves, now a PhD student at the University of Manchester, used modern computational methods to explore how all these marine reptiles divided up the spoils.

Jane said: “It’s difficult to work out the ecology and function of fossil animals but we decided to focus mainly on their feeding and swimming styles. I tracked down information on 371 of the best-known Mesozoic marine tetrapods, and coded each one for 35 ecological traits, including body size, diet, likely hunting style, tooth type, presence or absence of armour, limb shape and habitat.”

The numerical analysis showed that all these marine reptiles could be divided into just six ecological categories linking how they moved, where they lived, and how they fed: pursuit predators that chased their prey, ambush predators that lurked and waited for the prey to swim past (two groups, one in deep water, one in shallow), a fourth group of reptiles that could still walk on land, shallow-water shell-crushers and foragers, and marine turtles with a variety of life modes.

Professor Mike Benton, who co-supervised the study, said: “A problem with studies of form and function of fossils is that we have to be careful in reconstructing the behaviour of ancient animals. But in Jane’s study, she used ecological characters from the start where their function had already been established. For example, sharp pointy teeth mean fish-eating, whereas broad, flat teeth mean shell crushing.”

Mesozoic marine tetrapod ecospace. Animals in each group share ecological characteristics. They came in many shapes and sizes and had great variation in feeding apparatus. Credit: Tom Stubbs, University of Bristol

Dr Ben Moon, another co-supervisor, said: “We knew that the different marine reptile groups came and went through the 186 million years of the Mesozoic.

“I’m especially interested in ichthyosaurs, and we wanted to test an idea that they had migrated through ecospace during the Mesozoic. Jane’s study shows definite movement through time from being semi-terrestrial at the beginning of the Triassic to a wide range of ecologies, including ambush hunting, and finally pursuit predation in the Jurassic and Cretaceous.”

Dr Tom Stubbs, another co-supervisor, said: “We also wanted to test whether all these animals were competing with each other. But in fact, they seem to have avoided competition.

“For example, after a substantial extinction of marine reptiles around the end of the Triassic, the surviving ichthyosaurs and plesiosaurs showed considerable conservatism. They didn’t expand their ecological roles at all, and many niches were left empty until new groups of crocodiles and turtles emerged later in the Jurassic to take over these roles.”

Jane Reeves added: “It was a great experience being able to study a large variety of creatures, and to then reconstruct the ecological lifestyles of extinct animals from just their fossils.

“You do have to be very careful in doing these kinds of studies, not to make any unfounded assumptions. We know animals can be opportunistic, and don’t always behave exactly how we think they should, but we’re confident that the data we collected reflects the most common, day-to-day, behaviours of each animal. These results give us a great insight into what was really happening under the surface of the Mesozoic seas.”

This research was part funded by the Natural Environment Research Council (NERC) and the European Research Council (ERC).

References: Jane C. Reeves, Benjamin C. Moon, Michael J. Benton, Thomas L. Stubbs, “Evolution of ecospace occupancy by Mesozoic marine tetrapods”, Online Wiley Library, Paleontology, 2020
https://doi.org/10.1111/pala.12508

Provided by University of Bristol