Study of Antarctic Fossils Provides Evidence for Rapid Extinction

The demise of the non-avian dinosaurs, their flying reptile cousins, many marine vertebrates and a whole host of other flora and fauna some 66 million years ago has been well documented.  However, debate still rages over the cause or the causes of this mass extinction event at the Cretaceous-Palaeogene (K-Pg) boundary.  Was this extinction sudden and dramatic, caused by a catastrophic event such as an extraterrestrial impact or was it a gradual decline with many genera becoming extinct but over a longer period of time, perhaps as a result of global climate change?

Antarctic Fossils

A new study published recently in the journal “Nature Communications” suggests that the extinctions were rapid.  Analysis of sediment from Seymour Island in the Antarctic Peninsula indicates that there was a rapid and severe decline in marine fauna, this study supports the hypothesis that rather than a slow, gradual decline the K-Pg boundary represents a very rapid mass extinction event.

A Dramatic Reduction in the Number and Variety of Fossils

The white strip represents the Cretaceous-Palaeogene boundary.

Picture credit: Leeds University

Working on the remote Seymour Island in Antarctica, scientists from Leeds University along with researchers from the British Antarctic Survey, mapped and explored a series of highly fossiliferous marine sediments that date from approximately 69 million years ago through to around 65 million years ago.

Recording an Extinction Event Thanks to Antarctic Fossils

James Witts, a PhD student in the School of Earth and Environment (Leeds University), lead author of the scientific paper, was instrumental in identifying the various fauna that the 6,000 fossils represented.  It was then a case of ensuring that the fossils were documented in the correct stratigraphic sequence and from this, the researchers were able to conclude that there was a sudden reduction in the number of species living in Antarctic waters some 66 million years ago.  Around two thirds of the species disappear from the fossil record, at a time that coincides with the dinosaur extinction (K-Pg boundary).

In the picture above the K-Pg boundary is represented by the white paper strip.  There is a band of rocks in which no fossils can be found and in younger sediments deposited later, only a handful of different species are represented

A Sudden and Catastrophic Event

Student James commented:

“Our research essentially shows that one day everything was fine, the Antarctic had a thriving and diverse marine community and the next, it wasn’t.  Clearly, a very sudden and catastrophic event had occurred on Earth.  This is the strongest evidence from fossils that the main driver of this extinction event was the after-effects of a huge asteroid impact, rather than a slower decline caused by natural changes to the climate or by severe volcanism stressing global environments.”

A Rich and Diverse Maastrichtian Marine Ecosystem

This study is the first to conclude that the mass extinction that marked the end of the dinosaurs, pterosaurs and many other forms of life, was a truly global event and that it was just as sudden in high latitudes as it was in lower latitudes.  In short, the polar ecosystems were hammered too.

The fossils from the Late Maastrichtian strata that pre-date the extinction event indicate a rich and highly diverse marine food web populated by a huge array of molluscs such as gastropods, bivalves and cephalopods.  In turn, there were large numbers of different types of fish, the fish shared the shallow sea with a variety of marine reptiles including mosasaurs.  Numerous soft bodied organisms such as sea slugs, anemones, starfish and jelly fish would also have been present but their remains are not frequently preserved as fossils.

Peculiar Mollusces – Unravelling Ammonites

One of the more peculiar molluscs known from the Upper Cretaceous rocks of Seymour Island is the giant ammonite Diplomoceras.  This invertebrate, related to modern day cuttlefish and squid had a shell that uncoiled to a large extent.  It resembled a two-metre-long paper clip.  Although Diplomoceras fossils are found in rocks older than 66 million years, just like the rest of the ammonites, its fossils are absent in rocks laid down in the Palaeogene Epoch.

For models and replicas of ammonites and other prehistoric creatures: CollectA Prehistoric Life Figures.

An Illustration of the Bizarre Ammonite Diplomoceras

The bizarre Late Cretaceous ammonite Diplomoceras.

Picture credit: James McKay

Although the majority of ammonites had coiled shells, a number of families evolved in the Early Cretaceous with shells that were uncoiled to varying degrees.  In 2012, Everything Dinosaur wrote an article detailing research undertaken by scientists from the Natural History Museum of Vienna that provided an explanation for this adaptation.

To read more: Unravelling the Mystery of the Unravelling Ammonite.

A Rich and Diverse Marine Fauna – Prior to the Extinction Event

A rich and diverse marine fauna preserved in the strata of Seymour Island.

Picture credit: Leeds University

Everything Dinosaur acknowledges the help of Leeds University in the compilation of this article.  This blog post has also been constructed with reference to the academic paper: “Macrofossil evidence for a rapid and severe Cretaceous–Paleogene (K–Pg) mass extinction in Antarctica”, published in the journal Nature Communications in May 2016.

Visit Everything Dinosaur’s website: Everything Dinosaur.

Wahlisaurus massarae – A New Species of Early Jurassic Ichthyosaur

Manchester based palaeontologist Dean Lomax, has identified a new species of extinct marine reptile from a near complete fossil specimen discovered in an old Nottinghamshire quarry (East Midlands).  The fossil had been found many years ago and acquired by Leicester’s New Walk Museum back in 1951.  It is an ichthyosaur fossil.

However, the unusual deposition of the specimen, the carcase seems to have “nosedived” into the seabed prior to permineralisation, had prevented a new species of English marine reptile surfacing until now.

An Illustration of the Newest Member of the Ichthyosauria – Wahlisaurus massarae

New species of Early Jurassic Ichthyosaur announced.

Picture credit: James McKay

Rare Early Jurassic Ichthyosaur Fossil Find

Award winning palaeontologist Dean Lomax, an Honorary Scientist at the University of Manchester, took the opportunity to examine the specimen whilst visiting the New Walk Museum, he noticed a number of anomalies such as the morphology (shape) of some of the fossil bones.  The location of the fossil find (Nottinghamshire) and the age of the strata from which the fossils were collected, led him to suspect that this specimen might represent a new species of marine reptile.

Dean commented:

“When I first saw this specimen, I knew it was unusual.  It displays features in the bones – especially in the coracoid (part of the pectoral girdle) – that I had not seen before in Jurassic Ichthyosaurs anywhere in the world.  The specimen had never been published, so this rather unusual individual had been awaiting detailed examination.”

Visit the website of Dr Dean Lomax: British Palaeontologist Dr Dean Lomax.

The Nottinghamshire Ichthyosaur Fossil

The Nottinghamshire ichthyosaur fossil consists of skull elements, pectoral bones, limbs, bones from the pelvis, ribs and vertebrae.   It dates from the earliest part of the Jurassic, some 200 million years ago, (the Hettangian faunal stage).  Only a handful of ichthyosaur species are known from the very Early Jurassic.

Dean’s discovery is significant and it is helping scientists to map the radiation and diversity of the Ichthyosauria during the Early Jurassic.  It is also the first time a species of this geological age has been found outside the counties of Somerset and Dorset.

Adding to Our Knowledge or Early Jurassic Marine Reptiles

Publishing in the “Journal of Systematic Palaeontology”, this new species will contribute to our understanding of ichthyosaur species diversity, and their geographical distribution after the End Triassic extinction phase.  Recently, Everything Dinosaur published an account of Sclerocormus parviceps, a basal ichthyosauriform from eastern China whose fossils are some fifty million years older than those of Wahlisaurus.  Sclerocormus indicates that marine fauna recovered relatively quickly after the devastation of the End Permian mass extinction event.

To read more about the bizarre whip-tailed, “Black Sheep of the ichthyosaur Family”: The “Black Sheep” of the Ichthyosaur Family.

Ichthyosaur Fossils Can be Found at Various Locations in the British Isles

The Nottingham ichthyosaur (P. applebyi).  Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Palaeontologist and curator at the New Walk Museum, Dr Mark Evans stated:

“Parts of the skeleton had previously been on long-term loan to Ichthyosaur specialist and former museum curator D. Robert Appleby, and had only returned to the museum in 2004 after he sadly passed away.  He was clearly intrigued by the specimen, and although he worked on it for many years, he had identified it as a previously known species but never published his findings.”

Dean has named the new species Wahlisaurus massarae in honour of two palaeontologists (Professor Judy Massare and Bill Wahl), who have contributed significantly to the study of ichthyosaurs, and who first introduced Dean to studying them.  It was Professor Massare who co-authored a scientific paper on a new species of marine reptile from the Lower Jurassic of West Dorset that led to a the naming of an Ichthyosaurus species in honour of the 19th Century fossil hunter Mary Anning.

To read an article about Ichthyosaurus anningae: New Ichthyosaurus Species Honours Mary Anning.

Commenting on how he was inspired over the choice of name for the Nottinghamshire specimen, Dean said:

“Both Judy and Bill have been tremendous mentors for me.  They have significantly contributed to palaeontology, especially the study of ichthyosaurs, and I cannot think of a better way to remember them by naming this new ichthyosaur in their honour.  Their names will be set in stone forever, pun intended!”

The First British Early Jurassic Ichthyosaur Since Excalibosaurus

W. massarae is the first new genus of ichthyosaur from the British Early Jurassic to be described since Excalibosaurus (E. costini) in 1986.  Excalibosaurus is known from two specimens found at a beach locality in Somerset, “Excalibur lizard” is named after the animal’s elongated snout (rostrum), that reminded the researchers of the magical sword associated with Arthurian legend.

A Model of Excalibosaurus (CollectA Excalibosarus Model)

The CollectA Excalibosaurus model.

To view models of ichthyosaurs such as Excalibosaurus (whilst stocks last):

A spokesperson from Everything Dinosaur commented: CollectA Age of Dinosaurs Models.

“Hundreds of thousands of people will visit beaches around the United Kingdom over the next few weeks of summer, but very few will be aware of the rich ichthyosaur fossil heritage that such locations have.  The United Kingdom remains one of the world’s most important sites for Early Jurassic ichthyosaur discoveries and as the Nottinghamshire specimen proves, you don’t have to visit the seaside to find marine reptile fossils.”

This article has been compiled with reference to: “A new leptonectid Ichthyosaur from the Lower Jurassic (Hettangian) of Nottinghamshire, England, UK, and the taxonomic usefulness of the Ichthyosaurian coracoid”, by Dean Lomax, Journal of Systematic Palaeontology, 2016, published by Taylor & Francis Group.

Visit Everything Dinosaur’s website: Everything Dinosaur.

Indian Geologists Discover Dinosaur Footprints

A team of scientists including geologists from the University of Jai Narain Vyas, (formerly known as University of Jodhpur) have discovered a series of three-toed dinosaur footprints in exposed sandstones close to the town of Jaisalmer in the State of  Rajasthan (western India).  The well-preserved fossils represent an unknown type of meat-eating dinosaur, the prints have been assigned to the ichnogenus Eubrontes.

Dinosaur Footprints

Different Types of Three-toed Dinosaur Footprint

Theropod print compared to an ornithopod print.  Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

An ichnogenus, is a genus assigned to an organism that is only known from its trace fossils, in this case from its fossilised footprints.  The Eubrontes ichnogenus specifically refers to theropod fossilised prints and trackways that are associated with Upper Triassic and Early Jurassic strata.  At the time of writing, Everything Dinosaur team members are not aware of a precise dating for the strata, but extensive surveys mapping the numerous ammonite genera associated with the marine strata of the Jaisalmer district and specifically the Baisakhi Formation, indicate that the rocks in this part of the world were laid down during the Jurassic.

Eubrontes – A “Taxonomic Wastebasket”

One of the great problems with trace fossils such as a dinosaur footprint, is that it is extremely difficult to assign a species, a genus or even a family to it.  Unless the organism that made the trace is found at the end of the trackway then it is extremely difficult to classify a print such as the ones found in Rajasthan.

Claw marks indicate a meat-eater and the field team members have suggested that the dinosaur that walked across a sandy beach many millions of years ago might have been between five to seven metres in length with a hip height of around two and a half metres or thereabouts, but in the absence of body fossils such as bones and teeth, this is about as good as it is going to get.

Dinosaur Footprints and the Eubrontes Ichnogenus

Dinosaur footprints assigned to the Eubrontes genus have been found all over the world.  The most famous Eubrontes ichnogenus site is in the western United States, at the St George Dinosaur Discovery Site at Johnson Farm in Utah.  Everything Dinosaur has created a teaching exercise all about how to interpret fossil footprints based on the fossilised trackways found at this location.

To read more about how trace fossils can help to inspire schoolchildren: Humans and Dinosaurs a “Handy” Way to Tell the Difference.

Geologist Virendra Singh Parihar (University of Jai Narain Vyas), hopes that these fossils, along with other fossil material representing crocodiles, gastropods and fish that come from the marine deposits, will help to establish this region of the Thar Desert in western India as an important site for palaeontological research.

A Model of a Typical Jurassic Theropod Dinosaur

Middle Jurassic theropod dinosaur.  A model of Monolophosaurus.

The model (above) comes from the Wild Safari Prehistoric World range of figures: Wild Safari Prehistoric World Models.

The picture above shows a model of the carnivorous dinosaur Monolophosaurus, a member of the Tetanuran theropod clade, the tracks in India could have been made by a dinosaur that looked something like this.