Two remarkable juvenile Pterodactylus fossils have helped researchers to solve a puzzle concerning the Upper Jurassic deposits at Solnhofen. The Upper Jurassic Solnhofen archipelago of Germany has yielded a pterosaur assemblage that has long underpinned and continues to dominate much of our understanding of these Mesozoic flying reptiles.  Pterosaur fossils from this location broadly fit into two categories.  Firstly, there are the highly fragmentary fossils of adult, or sub-adults.  Often a specimen is represented by a single bone.  Secondly, there are the numerous very young pterosaurs* that are preserved almost intact and articulated.

A detailed analysis of two remarkable hatchling Pterodactylus fossils has helped scientists to put forward a plausible theory as to why these two types of fossil preservation, driven by ontogeny occurred.  They postulate that these two baby pterosaurs perished in a violent storm.  Young pterosaurs were caught in powerful tropical storms. Ironically, these powerful storms also created the ideal conditions to preserve their remains and hundreds more.

A hatchling Pterodactylus caught in a storm. Picture credit: Rudolf Hima.

Picture credit: Rudolf Hima

The Mystery of the Hatchling and Juvenile Pterodactylus Specimens

The researchers, including scientists from the University of Leicester discovered broken humeri in the fossilised remains of two hatchling pterosaurs.  These very young flying reptiles suffered broken wings.  The cause of death for these pterosaurs nicknamed “Lucky I” and “Lucky II” by the researchers, has been revealed.  Consider this a post-mortem on events that took place in the Late Jurassic around 150 million years ago.

Writing in the academic journal “Current Biology”, the team highlight that the preservation bias for large, more robust specimens was turned on its head in the waters of the Solnhofen lagoon.  Small delicate animals such as a juvenile Pterodactylus would rarely make it into the fossil record.  However, occasionally nature conspires to produce the conditions that permit the preservation of diminutive pterosaurs.

Lead author of the paper, Rab Smyth (University of Leicester) explained:

“Pterosaurs had incredibly lightweight skeletons. Hollow, thin-walled bones are ideal for flight but terrible for fossilisation. The odds of preserving one are already slim and finding a fossil that tells you how the animal died is even rarer.”

Examining the Tiny Fossils Under UV Light

Examination of the tiny fossils under UV light revealed the presence of broken upper arm bones (humeri) in the two specimens.  These details, easily overlooked, provided the evidence that their wings were subjected to a strong twisting force.  This was probably caused by a strong gust of wind rather than a collision against a hard surface.

Broken bones offer clues to the perils of pterosaur flight. Skeletal reconstructions of the two Pterodactylus hatchlings are shown in flight position, with broken bones marked in red. UV images reveal clear breaks in the upper arm bones. A silhouette of a house mouse (Mus musculus) is included for scale. Picture credit: Smyth et al (University of Leicester).

Picture credit: Smyth et al (University of Leicester)

The picture (above) shows fossil specimen MBH 250624-07 (Lucky I) as (A) part and (B) counterpart.  They are photographed under UV light.  The broken left humerus is in a predominantly ventral view, with the skull exposed in lateral view. Images C and D show the part and counterpart of Lucky II (SNSB-BSPG 1993 XVIII 1508 a/b), photographed in ventral view.  The fossil has a fractured right humerus.

Skeletal reconstructions of Lucky I (E) and Lucky II (F) along with a silhouette of a house mouse (Mus musculus) to provide scale.

Highlighting how Local Environmental Conditions can Distort the Fossil Record

The skeletons are virtually complete and articulated. Except for one small detail. Both specimens show the same unusual injury – a clean, slanted fracture to the humerus. Lucky’s left wing and Lucky II’s right wing were both broken in a way that suggests a powerful twisting force.  The researchers postulate that these unfortunate flying reptiles were caught up in a storm.

Pterosaur fossil preservation in the Solnhofen deposits. (A) Most of the time, pterosaurs stood little chance of becoming fossils. Decaying larger individuals sometimes left behind scattered bones that reached the lagoon floor, but smaller pterosaurs were usually lost without trace. (B) Storms, however, created very different conditions. Powerful winds and waves dragged the bodies of small and young pterosaurs into deeper waters. At the same time, these storms stirred up salty water from the lagoon floor. This water contained almost no oxygen, and when it mixed with the surface waters, it triggered sudden die-offs of marine life. These toxic waters acted as a barrier to scavengers and decay, allowing pterosaur bodies to sink largely untouched. The final step came when lime-rich mud, carried by the storm, rapidly buried the remains. This quick covering not only protected soft tissues from decay but also preserved fragments of larger pterosaurs that had been deposited earlier. Together, these rare conditions explain why fossils from Solnhofen are so well preserved. Picture credit: Smyth et al (University of Leicester).

Picture credit: Smyth et al (University of Leicester)

Catastrophically injured, the pterosaurs plunged into the surface of the lagoon, drowning in the storm driven waves and quickly sinking to the seabed where they were rapidly buried by very fine limy muds stirred up by the violent storm events. This rapid burial allowed for the remarkable preservation seen in their fossils.  The researchers have highlighted how local environmental conditions can lead to distortions in the fossil record.

Ironic Names for Juvenile Pterodactylus Fossils

Lucky I and Lucky II are ironic nicknames for these pterosaur fossils.  These animals may only have been a few days or weeks old when they perished.  There are many other small pterosaurs preserved in the Solnhofen limestone deposits.  These too, might present very young flying reptiles.  They may not demonstrate obvious signs of skeletal trauma but they could have met a similar fate as Lucky I and Lucky II. Unable to resist the strength of storms these young pterosaurs were also flung into the lagoon. This discovery may explain why smaller fossils are so well preserved – they were a direct result of storms – a common cause of death for pterosaurs that lived in the region.

Larger, stronger individuals, it seems, were able to weather the storms and rarely followed the Luckies stormy road to death. They did eventually die though but likely floated for days or weeks on the now calm surfaces of the Solnhofen lagoon, occasionally dropping parts of their carcasses into the abyss as their bodies slowly decomposed.

Rab Smyth added:

“For centuries, scientists believed that the Solnhofen lagoon ecosystems were dominated by small pterosaurs. But we now know this view is deeply biased. Many of these pterosaurs weren’t native to the lagoon at all. Most are inexperienced juveniles that were likely living on nearby islands that were unfortunately caught up in powerful storms.”

The researchers conclude that catastrophic storm sampling explains the high numbers of small, potentially juvenile pterosaurs preserved in the Solnhofen deposits.  This study also has implications for the perceived flight abilities of very young flying reptiles.  Wing injuries in neonatal pterosaurs were likely caused by violent storm events and this research supports precocial flight ability.

A “Lucky” Break

Co-author of the paper, Dr David Unwin (University of Leicester) commented:

“When Rab spotted Lucky we were very excited but realised that it was a one-off. Was it representative in any way? A year later, when Rab noticed Lucky II we knew that it was no longer a freak find but evidence of how these animals were dying. Later still, when we had a chance to light-up Lucky II with our UV torches, it literally leapt out of the rock at us – and our hearts stopped. Neither of us will ever forget that moment.”

*very young pterosaurs – there is some debate over whether the fossils all represent hatchlings or very young animals.  In addition, describing these two specimens as representatives of the taxon Pterodactylus has drawn criticism.  It has been suggested that this study could have included a detailed phylogenetic analysis rather than assign the two fossil specimens to what has been referred to as a “taxonomic wastebasket”.

Everything Dinosaur acknowledges the assistance of a media release from the University of Leicester in the compilation of this article.

The scientific paper: “Fatal accidents in neonatal pterosaurs and selective sampling in the Solnhofen fossil assemblage” by Robert S.H. Smyth, Rachel Belben, Richard Thomas and David M. Unwin published in Current Biology.

The award-winning Everything Dinosaur website: Everything Dinosaur.

Scientists including researchers from the Museum für Naturkunde (Berlin) have identified the oldest leaf mines in the fossil record. In addition, evidence of insect egg deposits has been found in association with these ancient trace fossils. Insect trace fossils in the studied fossil materials are so abundant that the researchers state that this is the oldest evidence of an insect infestation known to science.  The plant fossils examined in this ground-breaking research come from several museum collections.  The trace fossils record the highly specialised behaviour of insect larvae that lived approximately 295 million years ago.

The research, published in the journal “Scientific Reports” indicates that this specialised feeding behaviour had evolved at least forty million years earlier than previously thought.

The oldest leaf mines (Asteronomus maeandriformis) known to science. A plant fossil from the Permian period collected in Thuringia (left). Leaf mines of the leaf miner fly Liriomyza on a sow thistle (right). Picture credit: Laaß et al (Museum für Naturkunde Berlin).

Picture credit: Laaß et al (Museum für Naturkunde Berlin)

The Advantages of Being a Leaf Miner

In the late spring and summer evidence of the activity of insect larvae feeding inside the leaves of plants is easy to find. The insects produce distinctive channels in the surface of the leaf. Living inside plant tissue has many advantages. For example, the larvae are protected from predators, and they are less prone to harmful infections. In addition, they avoid dehydration, and the larvae have an almost inexhaustible supply of food all around them.

Today, leaf mines are produced exclusively by insects such as beetles, dipterans (flies), wasps and butterflies.  They undergo complete transformation (metamorphosis) and are therefore referred to as holometabolous insects. Holometabolous insects have four stages:

• Egg
• Larva
• Pupa
• Adult

Holometabolous insects are highly adaptable and extremely numerous. They have evolved slender, maggot-like larvae without body appendages that are optimally adapted to life inside plant tissue.

Until now, it was unclear when this sophisticated and highly successful strategy emerged in the Insecta. Previously, the oldest reliable evidence of leaf mines came from plant fossils from the Triassic.  This new study identifies for the first time leaf mining in Palaeozoic fossils.  These oldest leaf mines highlight the importance of conserving museum collections.

The Oldest Leaf Mines

The researchers from the natural history museums in Berlin, Chemnitz, Münster and Osnabrück, the TU Bergakademie Freiberg and Martin Luther University Halle-Wittenberg have been able to prove, leaf mining behaviour occurred more than forty million years earlier than previously thought. The extensive plant fossil collections from the natural history museums in Schleusingen, Berlin and from the Freiberg University collection were examined. These collections contained numerous exceptionally well-preserved specimens of the feeding traces of Asteronomus maeandriformis on leaves of the seed fern Autunia conferta.

The plant fossils come from the coal fields in Crock, Thuringia. These deposits, representing ancient swamps, were laid down in the Early Permian. Close scrutiny of the specimens permitted the team to conclusively prove leaf mining behaviour. In addition, the team identified many of the egg deposits associated with the feeding tunnels, which in some cases even contained the remains of insect eggs.

Numerous types of plants today have extremely ancient lineages.  For example, horsetails (Equisetum) continue to thrive as they are able to grow in areas where other plants would find it difficult to get a foothold. Often regarded as weeds, these tough little plants are essentially living fossils as the earliest examples of the genus Equisetum date from the Early Jurassic of South America. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Over Eighty Percent of the Fossil Autunia Plants Infested

Evidence of leaf mining was found in more than eighty percent of all the fossilised Autunia plants from Thuringia studied.

Palaeobotanist Ludwig Luthardt, one of the co-authors of the paper stated:

“Why exactly the Autunia plants in Crock were infested en masse remains largely a mystery. However, the phenomenon occurred at a time of global change, during which tropical terrestrial ecosystems gradually became drier. This shows how important it is to look to the past in times of current global climate change.”

Everything Dinosaur acknowledges the assistance of a media release from the Museum für Naturkunde Berlin in the compilation of this article.

The scientific paper: “Host-specific leaf-mining behaviour of holometabolous insect larvae in the early Permian” by Michael Laaß, Ludwig Luthardt, Steffen Trümper, Angelika Leipner, Norbert Hauschke and Ronny Rößler published in Scientific Reports.

The Everything Dinosaur website: Prehistoric Animal Models and Figures.

One of the world’s most unusual dinosaurs is even stranger than first thought.  Newly published research in the journal “Nature” confirms that the Moroccan armoured dinosaur Spicomellus afer is definitely an ankylosaur.  In addition, to the extremely spiky appearance, it probably had a tail weapon.  The evolution of a tail weapon predates this feature in any other known ankylosaur by more than thirty million years.  Furthermore, Spicomellus had a unique bony collar ringed with metre-long spikes sticking out from either side of its neck.

It has been nicknamed the “punk rock dinosaur”.

A Spicomellus life reconstruction in anterior view. Picture credit: Matthew Dempsey.

Picture credit: Matthew Dempsey

This dinosaur was formally named and described in 2021 (Maidment et al).  The initial description was made based on a single rib bone. The rib had spikes fused to it, a unique feature, not seen in any other animal.  However, the “T-shaped” cross section of the rib permitted the scientists to confidently assign this fossil to an ankylosaur.  Named Spicomellus afer, it represents Africa’s first known ankylosaur and the earliest representative of this iconic dinosaur clade (Ankylosauria).

To read Everything Dinosaur’s blog post from 2021 announcing the discovery of Africa’s first ankylosaur: The Earliest Ankylosaur and Africa’s First – Spicomellus.

The Remarkable Early Ankylosaur Spicomellus afer

The fossils are more than 165 million years old. This armoured dinosaur lived during the Middle Jurassic, near what is now the Moroccan town of Boulemane.  Further fossil discoveries have enabled the research team to learn more about this remarkable armoured dinosaur.  For example, they now know that Spicomellus had bony spikes fused onto and projecting from all of its ribs, a feature not seen in any other vertebrate species living or extinct. It had long spikes, measuring eighty-seven centimetres in length, which the researchers believe would have been even longer in real life.  These spikes emerged from a bony collar that sat around the reptile’s neck.

A fossil rib showing the spikes fused to it, a unique feature not seen in any other animal. Picture credit: The Trustees of the Natural History Museum, London.

Picture credit: The Trustees of the Natural History Museum, London

Professor Susannah Maidment of Natural History Museum, London, and the University of Birmingham, who co-led the team of researchers commented:

“To find such elaborate armour in an early ankylosaur changes our understanding of how these dinosaurs evolved. It shows just how significant Africa’s dinosaurs are, and how important it is to improve our understanding of them.”

Elaborate Dermal Armour

Ankylosaurs are best known from Late Cretaceous Northern Hemisphere ecosystems.  For instance, Ankylosaurus and Euoplocephalus are known from Upper Cretaceous rocks in the northern United States and Canada.  Ziapelta is known from fossils found in New Mexico, whereas Saichania, Pinacosaurus and Tarchia are known from Upper Cretaceous rocks in Asia.

“Sede” the Ankylosaurus dinosaur model.  The authors of the Spicomellus study postulate that with the emergence of larger predators this could have resulted in ankylosaur armour becoming simpler and more defensive.  Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The picture (above) shows a model of the Late Cretaceous ankylosaur Ankylosaurus magniventris.  The figure is from the Chinese manufacturer PNSO.

To view the range of PNSO models and figures in stock: PNSO Age of Dinosaurs Models.

The researchers postulate that the unique, elaborate spines and spikes of Spicomellus may have functioned for display as well as defence.  Later ankylosaurs had simpler armour with less extravagant osteoderms.  This might indicate a shift towards a primarily defensive function, perhaps in response to increased predation pressures or a switch to combative courtship displays.

Professor Maidment added:

“Spicomellus had a diversity of plates and spikes extending from all over its body, including metre-long neck spikes, huge upwards-projecting spikes over the hips, and a whole range of long, blade-like spikes, pieces of armour made up of two long spikes, and plates down the shoulder. We’ve never seen anything like this in any animal before. It’s particularly strange as this is the oldest known ankylosaur, so we might expect that a later species might have inherited similar features, but they haven’t.”

Professor Susannah Maidment of the Natural History Museum holding a rib with fused spikes. Picture credit: The Trustees of the Natural History Museum, London.

Picture credit: The Trustees of the Natural History Museum, London

Was There a Large Theropod in the Ecosystem?

There is another potential explanation for the remarkable armour associated with Spicomellus afer.  Could it have shared its environment with a large predator such as a theropod dinosaur?  There is certainly evidence to suggest that by the Middle Jurassic formidable tetanuran theropods were present in many ecosystems.

Co-author of the study, Professor Richard Butler (University of Birmingham) stated:

“Seeing and studying the Spicomellus fossils for the first time was spine-tingling. We just couldn’t believe how weird it was and how unlike any other dinosaur, or indeed any other animal we know of alive or extinct. It turns much of what we thought we knew about ankylosaurs and their evolution on its head and demonstrates just how much there still is to learn about dinosaurs”.

Professor Susannah Maidment of the London Natural History Museum and Professor Richard Butler (University of Birmingham) examine the fossil remains along with fellow researchers. Picture credit: The Trustees of the Natural History Museum, London.

Picture credit: The Trustees of the Natural History Museum, London

Did Spicomellus afer Have a Tail Club?

One feature of early ankylosaurs that may have survived, however, is their tail weaponry. While the end of Spicomellus’ tail has not be found, the caudal vertebrae that do survive suggest that it had a club or a similar tail weapon. Some of these tail vertebrae are fused together.  They form a structure referred to as a “handle”.  This feature has only been found in ankylosaurs that possessed a tail club.  If Spicomellus did have a tail club, it overturns current understanding regarding tail club evolution in the Ankylosauria.  These structures were previously thought to have first evolved in the Early Cretaceous.

The authors believe that the combination of a tail weapon and an armoured shield that protected the hips suggest that many of the ankylosaurs’ key adaptations already existed by the time of Spicomellus.

Spicomellus fossil material. This dinosaur was originally described in 2021, however, more fossils were excavated in 2023 providing the research team with further information about the bizarre anatomy of Spicomellus. Picture credit: The Trustees of the Natural History Museum, London.

Picture credit: The Trustees of the Natural History Museum, London

Improving Our Understanding of the Geographic Distribution of Armoured Dinosaurs

Finding more fossils of Spicomellus confirms its ankylosaurian affinities.  In addition, it helps to deepen our understanding of the geographic distribution of armoured dinosaurs. It also helps to spark public imagination in the Dinosauria as we learn more about the baffling characteristics of species like Spicomellus.

Professor Driss Ouarhache, lead of the Moroccan team from the Université Sidi Mohamed Ben Abdellah who co-developed the research, commented:

“This study is helping to drive forward Moroccan science. We’ve never seen dinosaurs like this before, and there’s still a lot more this region has to offer.”

The Spicomellus afer fossils that form the basis of this study were cleaned and prepared at the Department of Geology of the Dhar El Mahraz Faculty of Sciences in Fez, Morocco, using scientific equipment provided by the University of Birmingham’s Research England International Strategy and Partnership Fund. The fossils are now catalogued and stored on this site.  Perhaps, they will be put on display so that the public will have the opportunity to view these amazing fossils.

Everything Dinosaur acknowledges the assistance of a media release from the University of Birmingham in the compilation of this article.

In addition, Everything Dinosaur acknowledges the assistance of the London Natural History Museum for the use of their images.

The scientific paper: “Extreme armour in the world’s oldest ankylosaur” by Susannah C. R. Maidment, Driss Ouarhache, Kawtar Ech-charay, Ahmed Oussou, Khadija Boumir, Abdessalam El Khanchoufi, Alison Park, Luke E. Meade, D. Cary Woodruff, Simon Wills, Mike Smith, Paul M. Barrett and Richard J. Butler published in the journal Nature.

The award-winning Everything Dinosaur website: Everything Dinosaur.