Tag: fossil

Ancient Penguin Fossils Offer New Window into Antarctica’s Changing Climate

A team of palaeontologists studying penguin fossils from Seymour Island have demonstrated how ancient bird bones can act as chemical archives of past climate change.

A team of palaeontologists from China University of Geosciences (Beijing) studying penguin fossils from Seymour Island off the Antarctic Peninsula have demonstrated how ancient bird bones can act as chemical archives of past climate change.

The researchers used non-destructive X-ray mapping to examine the elemental composition of penguin remains spanning millions of years. As such, they uncovered key insights into how Antarctica shifted from a warm and humid environment to a cooler world.

“Penguins are among the most iconic animals of Antarctica and represent one of the most distinctive groups of birds, having completely lost the ability to fly and instead using their flipper-like wings for swimming.

Seymour Island preserves one of the world’s richest and most stratigraphically continuous records of Eocene penguin fossils. These fossils span an important interval of Antarctic climate evolution, from the relatively warm and humid conditions of the early Eocene to the cooler climate of the middle and late Eocene.”
The Research Team

Sampling area – Tertiary Eocene La Meseta Formation on Seymour Island. Image credit: Boyang Xia et al.
Sampling area – Submeseta Formation on Seymour Island. Image credit: Boyang Xia et al.

To study the rare fossils without damaging them, the researchers used micro-X-ray fluorescence scanning to map chemical elements across the surface of the bones. The scans revealed clear differences in the chemical composition of bones from different geological periods.

Older fossils dating back roughly 55 million years contained significantly higher levels of titanium, silicon and potassium. The team linked these chemical patterns to intense land-based weathering and heavy runoff during an ancient warm period, whereas younger fossils from cooler periods showed much lower elemental signals.

“The most surprising result was that the early Eocene fossil showed substantially higher titanium, silicon and potassium signals.

Based on the stratigraphic, sedimentological and palaeoclimatic evidence, we interpret this pattern as being consistent with stronger continental weathering and terrestrial material input under the warm and humid conditions of the early Eocene.”

Analysing millions-of-years-old fossils presented distinct practical challenges:

“One of the main challenges was obtaining reliable elemental information without damaging the fossils.

The irregular shapes and curved surfaces of the fossil bones created practical difficulties during scanning. To minimise the influence of variations in surface height, we positioned the bones as horizontally as possible and maintained a relatively constant distance between the scanning head and the bone surface.”

Overview of the fossil specimens and the µ-XRF scanning area. Image credit: Boyang Xia et al.

Beyond tracking weather conditions on land, the scanning method also detected iron, manganese and sulphur patterns trapped within the bones, reflecting local chemical changes in the marine sediment as the fossils were buried over time.

The team additionally highlights that studying bone geochemistry offers a valuable tool for understanding historical Earth systems alongside traditional techniques such as marine sediment drilling and microfossil analysis.

“An important finding for us was that the elemental information preserved in penguin bones may record not only how external materials entered the bones, but also differences in weathering input, depositional conditions and early diagenetic environments.

We believe that fossils can provide an important complementary source of information for studying palaeoenvironmental changes on the Antarctic Peninsula.”

The study, published in the open-access journal Fossil Record, demonstrates how combining non-destructive chemical scanning with established geological context can unlock valuable environmental data from fossil collections, thus broadening the scope of future polar research.

Original source:

Xia B, Wu H, Li Q (2026) Eocene penguin fossils as archives of Antarctic weathering and climate change: insights from micro-X-ray fluorescence elemental mapping. Fossil Record 29(2): 575-587. https://doi.org/10.3897/fr.29.192319

For more articles on palaeontology, visit the Fossil Record website and follow the journal on BlueSky and Facebook.

A Cretaceous Cold Case: The mysterious affair at Mullurina Mayu (Bolivia)

This study reports a large bowl-shaped depression from Late Cretaceous fluvial deposits in Bolivia, associated with sauropod trackways.

Guest Blog Post by Lara Sciscio and Christian A. Meyer

This study, published in Fossil Record, reports a large bowl-shaped depression from Late Cretaceous fluvial deposits in Bolivia, associated with sauropod trackways. Its morphology and scratch-like traces suggest a biogenic origin, possibly representing titanosaurid digging behaviour or an abandoned nest.

A good mystery always starts with a clue of something that was or shouldn’t have been…

Drone overview of the outcrop in the western part of the Maragua Syncline, Bolivia. Can you spot the palaeosurface with titanosaurid trackways?

The sun beats down on the Bolivian Altiplano as we walk across the rocky grey expanse of a now ancient riverbed, following a trail of fossil sauropod dinosaur tracks. We are in the Maragua region, near Sucre, in the heart of Bolivia.

Studying the trackways, we know they were made by titanosaurs, one of the largest long-necked dinosaurs to have walked the Earth. Then we stop. Within these trackways there lies a large bowl-shaped depression, seemingly carved into the rock. It is ~4 metres wide and over half a metre deep with a frayed, ragged margin.

It is unlike anything our ichnologist eyes have seen before.

Drone view of the Mullurina Mayu surface with the circular structure. Parallel sauropod (titanosaurid) trackways diagonally cut across the surface. Two people are the base of the outcrop are for scale.

Stepping closer, we realise that this is a rare oddity cut into the palaeosurface, and a slew of questions arises: Is this hollow formed by weathering, carved by modern waters? Or is it something older, potentially dug by the largest animals to ever walk the Earth? And then frozen in time?

Excavating loose sand from the structure before taking close-up photos for 3D modelling. In the foreground are titanosaurid tracks.

These questions led us on a scientific detective hunt that stretched back 67 million years, to when titanosaurs walked this part of the Earth. And just short of the asteroid impact that would bring the “Age of Dinosaurs” to an end.

Weathering… or Dinosaurs?

Usually, when we encounter oddly shaped depressions in the rock record, ~99% of the time, the explanation for their formation is weathering and erosion. Nevertheless, you gather evidence and then use it to determine how and what happened. These were our first priorities on encountering the Mullurina Mayu bowl-shaped depression.

As we examined the site in detail, those potential abiotic explanations soon began to fall apart. Hydraulic scours usually have smooth walls and are aligned with the flow of water; weathering pits leave characteristic weathering textures and are grouped in smaller concentrations. This bowl structure had neither, and instead, we noticed many parallel grooves grouped in bundles and oriented around its walls and near its base.

It became evident that abiotic mechanisms were unlikely, and these potential abiotic tool marks (a type of sedimentary structure) were biotic in nature. The presence of these scratch-like marks, their shape, orientations, and distribution indicated that something had been digging.

Close-up of scratch-like marks within an imprint inside the depression (scale bar: 20 cm).

Fingerprints

Our evidence was not in the shape of the depression itself, but the multitude of scratch traces around its perimeter. The walls carried bundles of parallel grooves, ~1 cm wide, several cm’s long, and other isolated claw traces preserved in what would have been mud. These traces were not random but oriented in two directions and indicate movement of an animal’s autopod.

Scratch-like traces associated with sauropod tracks are features known to ichnologists, although a rarity, and have been encountered at several sites, from Colorado (USA), Spain, to Mongolia. Recent discoveries in Mongolia have shown that sauropod feet could leave detailed impressions of their keratinised scales (“fingerprints”). These produce distinct striations, and their patterning and the elongate incisions are evidence that their feet moved through or across the sediment.

The grooves in Bolivia closely resemble those skin-drag traces made by a scaled foot as it repeatedly scraped its feet through and across the muddy riverbank sediment. We infer this as behavioural evidence of an animal, and the most likely is the titanosaur which left its footprints nearby. We had found fingerprints of a titanosaur, excavating, but excavating what?

Building a nest?

This is a question that many may ask: could the titanosaurs be trying to construct a nest? The answer – maybe.

There is a limited body of evidence of nesting scrapes in the fossil record. They are described as depressions which cut into the original sediment (tick), have a distinct rim (tick), and would later be infilled with different sediment (tick!). The strongest evidence for a nest structure, however, would be the presence of eggs, eggshell, or embryos, and this is still missing at the Mullurina Mayu depression. This makes our assumption of nesting less confident.

Instead, we can use the evidence we have to say it was most likely a sauropod dinosaur, using its scaley feet, that excavated the ground, and one possible explanation is that this is an abandoned nesting attempt. Ichnologists advance only because we make careful probabilities rather than claiming certainties where evidence is absent. Nonetheless, this is an exciting discovery for what it shows and for where it leads our imaginations!

What were they doing?

Body fossils (bones) tell us what animals look like, tracks tell us how they moved, how big they may be, and traces like the Mullurina Mayu depression give us a small glimpse of what they were doing. The ichnological (trace) fossil record often captures moments of an animal’s life. Here, we can see a giant titanosaur scraping, digging, and interacting with the environment rather than just looking at its bones.

Whether it was nest scraping, digging for fresh water or mineral salts (like modern elephants) or carrying out some other behaviour we have yet to recognise, what we do know is that the most interesting fossils are not of the animals themselves but the traces of their behaviours, short time shots of their lives, frozen and fossilised in the rock record.

Cover image:

Artistic reconstruction of the Mullurina Mayu bowl-shaped depression during the Late Cretaceous, depicting the probable tracemakers responsible for the Calorckosauripus trackways and possibly the bowl-shaped depression. Illustration by Joshua Knüppe (commissioned 2025).

Original source:

Meyer CA, Heymann JH, Ibarra EC, Flores EL, Sciscio L (2026) Digging Sauropods: excavation behaviour or evidence for nest building? An example from the Late Cretaceous El Molino Formation (Maragua, Bolivia). Fossil Record 29(2): 519-532. https://doi.org/10.3897/fr.29.198794

For more articles on palaeontology, visit the Fossil Record website and follow the journal on BlueSky and Facebook.

Giant ichthyosaur with injuries discovered in Northern Bavaria, Germany

Based on its skull length of 1.5 meters, the animal is estimated to have been about 6.6 meters long.

The Mistelgau clay pit near Bayreuth, Germany, is known for its well-preserved marine fossils, particularly its abundance of ichthyosaurs. These large marine reptiles resembled modern dolphins in appearance and lived worldwide during the Early Jurassic period, around 180 million years ago.

The ichthyosaur from Mistelgau now under investigation belongs to the genus Temnodontosaurus. Several parts of its skeleton have been preserved: fragments of the skull and lower jaw, the shoulder girdle, forefins, the spine, and over 100 teeth. The exceptional three-dimensional preservation allows researchers detailed insights into anatomical structures that have rarely been documented before, such as those in the palate, orbital region, and the fins.

Comparisons reveal clear similarities, but also differences to Temnodontosaurus trigonodon—animals of this species are among the largest known ichthyosaurs. Based on its skull length of 1.5 meters, the animal is estimated to have been about 6.6 meters long. These findings are published in the open-access journal Zitteliana.

Fossil *Temnodontosaurus* cf. *trigonodon* (UMO BT 011237.00), viewed from below, showing the skull and body plate, including all isolated bones and teeth recovered from the surrounding sediment. Image credit: Urwelt-Museum Oberfranken.

“Our Temnodontosaurus fossil is one of the youngest finds of this ichthyosaur genus to date. Until now, representatives of this genus have mainly been known from older geological layers, such as the Posidonia Shale of Holzmaden. The discovery from Mistelgau now shows that these large marine reptiles survived longer in the Southwest German Basin than previously documented.”
Dr. Ulrike Albert, SNSB paleontologist

Albert conducts research at the Urwelt-Museum Oberfranken in Bayreuth, one of ten museums belonging to the Bavarian State Collections of Natural History. The team at the Urwelt-Museum Oberfranken has been conducting regular excavations in Mistelgau since 1998. The fossils recovered there are prepared at the Urwelt-Museum and subsequently subjected to scientific analysis.

Particularly striking are several modifications to the skeleton, presumably caused by injuries, including those affecting the reptile’s shoulder and jaw joints.

“The injuries likely significantly limited the animal’s ability to catch prey. The fact that it nevertheless survived is evidenced, among other things, by its heavily worn teeth and gastroliths, which we were able to identify in the abdominal region.”
Stefan Eggmaier, preparator at the Urwelt-Museum

Ulrike Albert and Stefan Eggmaier from the Urwelt-Museum Oberfranken at the excavation site in Mistelgau. Image credit: Mathias Orgeldinger.

Gastroliths are extremely rare in ichthyosaurs such as Temnodontosaurus. Eggmaier speculates that the animal may have had to change its diet in order to survive its injuries.

The current findings are part of ongoing research into the ecology of the Jurassic Sea in Upper Franconia. Analyses of teeth and bone structures are planned, with the aim of better understanding the ecology of these animals and their habitat.

Original study:

Eggmaier SA, Albert UEG (2026) A partial skeleton of Temnodontosaurus cf. trigonodon in three-dimensional bone preservation from the upper Toarcian of Mistelgau, Germany. Zitteliana 100: 39-80. https://doi.org/10.3897/zitteliana.100.172724

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