FOSSILS & DINOSAURS
Tracing Earth’s past in prehistoric rock deposits
IMAGE: OUTCROP OF THE PALAEOPROTEROZOIC SECTION IN THE CUDDAPAH BASIN view more
CREDIT: YOGARAJ BANERJEE
What did the Earth look like about two billion years ago, when the planet’s atmosphere was being oxygenated?
By analysing ancient dolomite (carbonate) deposits found in Vempalle, in the Cuddapah district of Andhra Pradesh, researchers at the Indian Institute of Science (IISc) and the University of Tennessee have estimated the temperature and composition of a shallow, inland sea that most likely existed back in that time, called the Palaeoproterozoic era.
Their findings provide insight into how the conditions during that time provided just the right ambience for the emergence and bloom of photosynthetic algae. It also shows how a wealth of data about our planet’s past remains hidden inside ancient rocks.
“The story of our planet is written in the different strata of rocks,” explains Prosenjit Ghosh, Professor at the Centre for Earth Science (CEaS), IISc, and corresponding author of the study published in Chemical Geology.
Planet Earth hasn’t always been this hospitable for life. It has been through different phases of climatic extremes, including periods when carbon dioxide levels were almost too toxic for living creatures, just like our neighbour, Venus. However, various studies of fossils from the Palaeoproterozoic era have shown that some life might have existed even under these harsh conditions.
The large amounts of CO2 in the atmosphere were absorbed by the sea and trapped as carbonates in dolomites, says Yogaraj Banerjee, a former PhD student from CEaS and one of the authors.
“[Dolomite] is a direct precipitate from seawater. It provides a signal not only of seawater chemistry but also of seawater temperature,” explains Robert Riding, Research Professor at the Department of Earth and Planetary Sciences, University of Tennessee, USA, and another author of the study.
The team of researchers collected dolomite samples from chert – hard rocks formed by the interaction of microbes with seawater – as well as deposits underneath them called dolomitic lime-mud. Having first identified the strata of rock where the dolomitic mud could be found, the researchers extracted and transported them back to the lab. Then, they used a state-of-the-art technique known as clumped isotope thermometry to analyse them. The technique allows scientists to narrow down the temperature and composition of the deposits by looking at the arrangement of the carbon and oxygen bonds.
After two years of intense analysis, the team was able to figure out from the dolomitic mud that the temperature of the seawater during its original time period was about 20°C. This is in contrast to previous studies that analysed only chert samples from around the same period, and had estimated that the temperature was higher, around 50°C. The lower temperature estimate from the current study agrees more closely with the theory that the conditions were ideal for supporting lifeforms.
During the Palaeoproterozoic era, the type of water present was earlier believed to be only heavy water, containing a specific set of isotopes or forms of hydrogen. However, in the current study, the team showed that light water – the regular form of water found even today – was also present back then.
Taken together, these insights – the lower seawater temperature and the presence of light water – strongly support the hypothesis that the conditions around two billion years ago were just right for photosynthetic algae to emerge. These algae were mainly responsible for pumping oxygen into the atmosphere, and making way for other lifeforms to evolve and populate the planet.
The team now plans to search for similar lime-mud deposits in other places around the world to gather additional insights about the Palaeoproterozoic era.
Palaeoproterozoic (around 2 billion years-old) stromatolite fossils studied in this project
CREDIT
Yogaraj Banerjee
JOURNAL
Chemical Geology
ARTICLE TITLE
Oxygen isotopic composition of Paleoproterozoic seawater revealed by clumped isotope analysis of dolomite, Vempalle Formation, Cuddapah, India
New details of Tully monster revealed
3D scanning of enigmatic fossil may have brought an end to debate about whether it is a vertebrate or invertebrate
Peer-Reviewed PublicationIMAGE: DISCOVERED IN THE 1950S AND FIRST DESCRIBED IN A PAPER IN 1966, THE TULLY MONSTER, WITH ITS STALKED EYES AND LONG PROBOSCIS, IS DIFFICULT TO COMPARE TO ALL OTHER KNOWN ANIMAL GROUPS. UNIQUE TO ILLINOIS IN THE U.S., IT BECAME ITS STATE FOSSIL IN 1989. view more
CREDIT: TAKAHIRO SAKONO, 2022.
For more than half a century, the Tully monster (Tullimonstrum gregarium), an enigmatic animal that lived about 300 million years ago, has confounded paleontologists, with its strange anatomy making it difficult to classify. Recently, a group of researchers proposed a hypothesis that Tullimonstrum was a vertebrate similar to cyclostomes (jawless fish like lamprey and hagfish). If it was, then the Tully monster would potentially fill a gap in the evolutionary history of early vertebrates. Studies so far have both supported and rejected this hypothesis. Now, using 3D imaging technology, a team in Japan believes it has found the answer after uncovering detailed characteristics of the Tully monster which strongly suggest that it was not a vertebrate. However, its exact classification and what type of invertebrate it was is still to be decided.
In the 1950s, Francis Tully was enjoying his hobby fossil hunting in a site known as Mazon Creek Lagerstätte in the U.S. state of Illinois, when he discovered what would later become known as the Tully monster. This 15-centimeter (on average), 300-million-year-old marine “monster” turned out to be an enigma, as ever since its discovery researchers have debated where it fits in the classification of living things (its taxonomic position). Unlike dinosaur bones and hard-shelled creatures that are often found as fossils, the Tully monster was soft-bodied. The Mazon Creek Lagerstätte is one of the few places in the world where the conditions were just right for imprints of these marine animals to be captured in detail in the underwater mud, before they could decay. In 2016, a group of scientists in the US proposed a hypothesis that the Tully monster was a vertebrate. If this was the case, then it could be a missing piece of the puzzle on how vertebrates evolved.
Despite considerable effort, studies both supporting and rejecting this hypothesis have been published in recent years, and so a consensus had not been reached. However, new research by a team from the University of Tokyo and Nagoya University may have finally brought an end to the debate. “We believe that the mystery of it being an invertebrate or vertebrate has been solved,” said Tomoyuki Mikami, a doctoral student in the Graduate School of Science at the University of Tokyo at the time of the study and currently a researcher at the National Museum of Nature and Science. “Based on multiple lines of evidence, the vertebrate hypothesis of the Tully monster is untenable. The most important point is that the Tully monster had segmentation in its head region that extended from its body. This characteristic is not known in any vertebrate lineage, suggesting a nonvertebrate affinity.”
The team studied more than 150 fossilized Tully monsters and over 70 other varied animal fossils from Mazon Creek. With the aid of a 3D laser scanner, they created color-coded, three-dimensional maps of the fossils which showed the tiny irregularities which existed on their surface through color variation. X-ray micro-computed tomography (which uses X-rays to create cross sections of an object so that a 3D model can be created), was also used to look at its proboscis (an elongated organ located in the head). This 3D data showed that features previously used to identify the Tully monster as a vertebrate were not actually consistent with those of vertebrates.
Although the researchers are confident from this study that the Tully monster was not a vertebrate, the next step of the investigation will be to answer what group of organisms it does belong to, possibly a nonvertebrate chordate (like a fishlike animal known as a lancelet) or some sort of protostome (a diverse group of animals containing, for example, insects, roundworms, earthworms and snails) with radically modified morphology.
Problematic fossils like the Tully monster highlight the challenge of piecing together the dynamic history of Earth and the diverse organisms that have inhabited it. “There were many interesting animals that were never preserved as fossils,” Mikami said. “In this sense, research on the fossils from Mazon Creek is important because it provides paleontological evidence that cannot be obtained from other sites. More and more research is needed to extract important clues from Mazon Creek fossils to understand the evolutionary history of life.”
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Paper Title:
Tomoyuki Mikami, Takafumi Ikeda, Yusuke Muramiya, Tatsuya Hirasawa, Wataru Iwasaki. Three-dimensional anatomy of the Tully monster casts doubt on its presumed vertebrate affinities Palaeontology 2023. DOI: 10.1111/pala.12646
Funding:
This research was supported by the Masason Foundation, Fujiwara Natural History Foundation, JSPS KAKENHI (grant numbers 18J21859 and 22J01214), and the World-Leading Innovative Graduate Study Program for Life Science and Technology.
Useful Links:
Graduate School of Science: https://www.s.u-tokyo.ac.jp/en/
Graduate School of Frontier Sciences: https://www.k.u-tokyo.ac.jp/en/index.html
Often used to study dinosaur footprints, these color-coded depth maps enabled the researchers to thoroughly investigate the structure of the Tully monster and other fossils from Mazon Creek.
CREDIT
Mikami, 2022.
JOURNAL
Palaeontology
METHOD OF RESEARCH
Imaging analysis
SUBJECT OF RESEARCH
Animals
ARTICLE PUBLICATION DATE
17-Apr-2023
Fossils reveal the long-term relationship between feathered dinosaurs and feather-feeding beetles
Amber fragments preserve remains of feathers and larvae related to modern feather-feeding beetles in intimate contact
Peer-Reviewed PublicationIMAGE: MOULT REMAINS OF FEATHER-FEEDING BEETLE LARVAE INTIMATELY ASSOCIATED WITH DOWNY FEATHER PORTIONS FROM AN UNIDENTIFIED THEROPOD DINOSAUR IN EARLY CRETACEOUS AMBER OF SPAIN. INSETS SHOW THE HEAD WITH POWERFUL MANDIBLES OF ONE OF THE LARVAL MOULTS (TOP) AND THE PIGMENTATION PATTERN OF FEATHER SECOND ORDER BRANCHES (BOTTOM), WITH THE MAIN STEM OF ONE FEATHER AT THE RIGHT OF THE AMBER FRAGMENT. AMBER FRAGMENT IS ONLY 6 MILLIMETRES ACROSS. view more
CREDIT: CN IGME-CSIC
New fossils in amber have revealed that beetles fed on the feathers of dinosaurs about 105 million years ago, showing a symbiotic relationship of one-sided or mutual benefit, according to an article published in Proceedings of the National Academy of Sciences of the United States of America today*.
The main amber fragments studied, from the Spanish locality of San Just (Teruel), contain larval moults of small beetle larvae tightly surrounded by portions of downy feathers. The feathers belonged to an unknown theropod dinosaur, either avian (a term referring to “birds” in wide sense) or non-avian, as both types of theropods lived during the Early Cretaceous and shared often indistinguishable feather types. However, the studied feathers did not belong to modern birds since the group appeared about 30 million years later in the fossil record, during the Late Cretaceous.
When looking at modern ecosystems, we see how ticks infest cattle, frogs capture insects with acrobatic tongues, or some barnacles grow on the skin of whales. These are just a few of the diverse and complex ecological relationships between vertebrates and arthropods, which have coexisted for more than 500 million years. The way that these two groups have interacted throughout deep time is thought to have critically shaped their evolutionary history, leading to coevolution. Nevertheless, evidence of arthropod-vertebrate relationships is extremely rare in the fossil record.
The larval moults preserved in the amber were identified as related to modern skin beetles, or dermestids. Dermestid beetles are infamous pests of stored products or dried museum collections, feeding on organic materials that are hard for other organisms to decay such as natural fibres. However, dermestids also play a key role in the recycling of organic matter in the natural environment, commonly inhabiting nests of birds and mammals, where feathers, hair, or skin accumulate.
“In our samples, some of the feather portions and other remains – including minute fossil faeces, or coprolites – are in intimate contact with the moults attributed to dermestid beetles and show occasional damage and/or signs of decay. This is hard evidence that the fossil beetles almost certainly fed on the feathers and that these were detached from its host,” explains Dr Enrique Peñalver, from the Geological and Mining Institute of Spain of the Spanish National Research Council (CN IGME-CSIC) and lead author of the study.
“The beetle larvae lived −feeding, defecating, moulting− in accumulated feathers on or close to a resin-producing tree, probably in a nest setting. A flow of resin serendipitously captured that association and preserved it for millions of years.”
“Three additional amber pieces each containing an isolated beetle moult of a different maturity stage but assigned to the same species were also studied, allowing a better understanding of these minute insects than what is usually possible in palaeontology,” says Dr David Peris, from the Botanical Institute of Barcelona (CSIC-Barcelona City Council) and co-author of the study. The most impressive, complete specimen was found in the amber deposit of Rábago/El Soplao in the northern Spain, roughly of the same age as San Just.
“It is unclear whether the feathered theropod host also benefitted from the beetle larvae feeding on its detached feathers in this plausible nest setting,” says Dr Ricardo Pérez-de la Fuente, from Oxford University Museum of Natural History and co-lead author of the study. “However, the theropod was most likely unharmed by the activity of the larvae since our data show these did not feed on living plumage and lacked defensive structures which among modern dermestids can irritate the skin of nest hosts, even killing them.”
Isolated moult of the feather-feeding beetle larva found in the Spanish amber outcrop of Rábago/El Soplao, with detail of its powerful mandibles (left). Length of the moult is less than two millimetres.
CREDIT
CN IGME-CSIC
Notes
(*) The paper “Symbiosis between Cretaceous dinosaurs and feather-feeding beetles” is published as open access in the journal Proceedings of the National Academy of Sciences of the United States of America (=PNAS). For accessing an embargoed copy of the original article, please refer to PNAS’ EurekAlert! press note at https://www.eurekalert.org/news-releases/985779
The international and multidisciplinary team comprised researchers from the Geological and Mining Institute of Spain of the Spanish National Research Council (CN IGME-CSIC), the Botanical Institute of Barcelona (IBB-CSIC), the University of Barcelona and the Institute for Research on Biodiversity (IRBio), the Complutense University of Madrid, the ‘Parque de las Ciencias’ of Andalusia, the Autonomous University of Madrid, and the Royal Academy of Exact, Physical and Natural Sciences (Spain); the American Museum of Natural History and the Natural History Museum of Los Angeles County (United States of America); the Senckenberg Research Institute (Germany); and Oxford University Museum of Natural History (United Kingdom).
Funding bodies: the project CRE, funded by the Spanish AEI/FEDER, UE Grant CGL2017-84419, the project PGC2018-094034-B-C22 (MCIU/AEI/FEDER, UE), the project CGL2014-52163, funded by the Spanish Ministry of Economy, Industry, and Competitiveness, the Secretary of Universities and Research of the Government of Catalonia and European Social Fund (2021FI_B2 00003), and the Consejería de Industria, Turismo, Innovación, Transporte y Comercio of the Gobierno de Cantabria through the public enterprise EL SOPLAO S.L.
For further information and images, please contact:
Dr Enrique Peñalver
Senior Researcher
Geological and Mining Institute of Spain of the Spanish National Research Council (CN IGME-CSIC)
Notes to editors
About Oxford University Museum of Natural History
Founded in 1860 as the centre for scientific study at the University of Oxford, the Museum of Natural History now holds the University’s internationally significant collections of entomological, geological and zoological specimens. Housed in a stunning Pre-Raphaelite-inspired example of neo-Gothic architecture, the Museum’s growing collections underpin a broad programme of natural environment research, teaching and public engagement.
JOURNAL
Proceedings of the National Academy of Sciences
METHOD OF RESEARCH
Experimental study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Fossils reveal the long-term relationship between feathered dinosaurs and feather-feeding beetles
ARTICLE PUBLICATION DATE
17-Apr-2023
How can a pollinating insect be recognised in the fossil record?
The oldest fossil record of pollination
Peer-Reviewed PublicationIMAGE: A SPECIMEN OF THE SPECIES MEIONEURITES SPECTABILIS FROM THE EXTINGUISHED FAMILYKALLIGRAMMATIDAE (NEUROPTERA). view more
CREDIT: XAVIER DELCLÒS - UNIVERSITY OF BARCELONA
Insect pollination is a decisive process for the survival and evolution of angiosperm (flowering) plants and, to a lesser extent, gymnosperms (without visible flower or fruit). There is a growing interest in studies on the origins of the relationship between insects and plants, especially in the current context of the progressive decline of pollinating insects on a global scale and its impact on food production. Pollinating insects can be recognized in the fossil record, although to date, there has been no protocol for their differentiation. Fossil pollinators have been found in both rock and amber deposits, and it is in rock deposits that the first evidence of plant pollination by insects is being studied across the globe. But how can we determine which was a true insect pollinator in the past?
A study published in the journal Trends in Ecology & Evolution determines the criteria for differentiating a pollinating insect from a presumed pollinator in the fossil record. This new study, which will facilitate the correct analysis of the origin and evolution of insect pollination, has been led by the doctoral student Constanza Peña-Kairath, first author of the paper and member of the Faculty of Earth Sciences and the Biosiversity Research Institute (IRBio) of the University of Barcelona. Peña-Kairath is working on the thesis under the supervision of Professor Xavier Delclòs (UB-IRBio) and researcher David Peris (Botanical Institute of Barcelona, CSIC - Barcelona City Council), who are also co-authors of the work.
Other experts from the UB-IRBio, the Spanish Geological and Mining Institute (CN-IGME CSIC), the American Museum of Natural History in New York (United States) and the University of Northampton (United Kingdom) have also participated in the article.
When "gymnosperms" dominated terrestrial ecosystems
Today, angiosperms dominate most of the planet's terrestrial ecosystems, but this has not always been the case: flowering plants appeared during the Lower Cretaceous and diversified during the Upper Cretaceous, about 100 million years ago, replacing forests dominated by "gymnosperms" (conifers, ginkgoes, cycads, etc.).
"Angiosperms are considered to have interacted with pollinating insects (a mutualistic relationship, with mutual benefits) since they appeared on the planet. Their first pollinators were probably generalist insects (beetles, thrips, flies, etc.) that had previously pollinated ‘gymnosperms’. In fact, several fossils are known in Cretaceous amber in which pollinating agents were probably already present", says Constanza Peña-Kairath, member of the UB Department of Earth and Ocean Dynamics.
How to classify an insect as pollinator?
Studying such a complex process as insect pollination through the fossil record is a challenge in palaeontology. In order to identify a pollinating species that inhabited past ecosystems, it is not possible to perform the analyses that are currently applied to organisms found in the natural environment (e.g. analysis of increased fruit formation on certain plants if visited by certain insects, etc.).
"Therefore, it is necessary to define when a fossil insect can be considered a pollinating agent and thus establish a whole set of key characteristics that can also be observed generally in fossils", says Peña-Kairath.
The study has identified 193 insect families from ten different orders that are considered to be pollinators of angiosperms and "gymnosperms". The authors have also established when they appear in the fossil record and have produced a classification of the fossil insects that have been described as pollinators to date.
By combining these scientific data, the team has developed a key to differentiate fossil insects into two categories —pollinator and presumed pollinator— and thus rule out those that do not show enough evidence of this type of mutualism with plants. Thus, in order to classify a fossil insect as a pollinator, the arthropod must have pollen grains attached to its body and belong to a group of present-day insects considered pollinators, among other characteristics.
Using the analysis of the entire fossil record, it is clear that all current insect orders with some pollinator species existed before the appearance of angiosperms in the Lower Cretaceous. There are even examples of insect groups that were pollinators during the Cretaceous —such as the Mecoptera or scorpionflies— but that no longer have pollinating species today.
The oldest fossil record of pollination
The conclusions of the study suggest that the earliest record of the mutualistic relationship involving insect pollination relates to an extinct group of Neuroptera insects and it originated at least in the Late Jurassic —some 163 million years ago— long before the emergence of the first flowering plants.
"This information is highly relevant because it reveals that insects have had a close relationship with gymnosperms since ancient times. Therefore, it comes as no surprise that some of these plants continue with this beneficial relationship today", conclude researchers Xavier Delclòs and David Peris.
An insect of the species <i>Buccinatormyia magnifica</i> from the extinguished family <i>Zhangsolvidae</i> (<i>Diptera</i>), El Soplao (Spain).
CREDIT
Enrique Peñalver
A bee next to a lavender flower.
CREDIT
Pol Delclò
Amber pieces from the archaeological site of El Soplao (Spain).
CREDIT
UNIVERSITY OF BARCELONA
JOURNAL
Trends in Ecology & Evolution
METHOD OF RESEARCH
Observational study
SUBJECT OF RESEARCH
Animals
ARTICLE TITLE
Insect pollination in deep time
ARTICLE PUBLICATION DATE
17 Apr-2023
