Baby Ichthyosaurus communis Dined on Squid

A team of UK-based scientists have identified the youngest and therefore the smallest specimen of Ichthyosaurus communis known to science and, just for good measure, they have found what could have been the marine reptile’s last meal.  Inside the body cavity of the seventy-centimetre-long fossil, the researchers found tiny “hook-like” structures, these are the less digestible parts of squid and therefore, the scientists were able to deduce that this young Ichthyosaurus had recently fed on cephalopods.

A Young Ichthyosaurus communis Attacking a Prehistoric Squid

A neonate Ichthyosaurus communis feeding on a squid.

A neonate Ichthyosaurus attacks a squid.

Picture Credit: Julian Kiely

The artist Julien Kiely has kindly reconstructed the new-born in this fantastic scene, which depicts the moment a newly born Ichthyosaurus communis attacks a squid.

Commenting on the significance of this discovery, one of the authors of the scientific paper, published today in the journal “Historical Biology – The International Journal of Paleobiology”, Dean Lomax stated:

“It is amazing to think we know what a creature that is nearly 200 million years old ate for its last meal.  We found many tiny hook-like structures preserved between the ribs.  These are from the arms of prehistoric squid.  So, we know this animal’s last meal before it died was squid.”

From the Biggest to the Smallest

University of Manchester palaeontologist Dean Lomax, in collaboration with German colleagues, had recently published a paper describing the largest specimen of Ichthyosaurus communis, a female that turned out to be pregnant when she died.  Everything Dinosaur wrote an article about the research in August*, as well as having described the biggest I. communis, just a few weeks later, this new paper, describes the smallest.

Palaeontologist Dean Lomax Holds the Neonate Ichthyosaurus communis Specimen

Dean Lomax holding the neonate Ichthyosaurus fossil.

Palaeontologist Dean Lomax holding the baby Ichthyosaurus fossil.

Picture Credit: University of Manchester/University of Birmingham

*To read the article about the largest Ichthyosaurus communis specimen: Palaeontologists and the Pregnant Ichthyosaurus

Ichthyosaurus communis

Several species of Ichthyosaurus have been identified, but Ichthyosaurus communis was the first, being named and described in 1822 from fossil material discovered by Mary Anning.  These reptiles were viviparous and a number of specimens showing embryos preserved inside their mothers are known.  However, this Ichthyosaurus is one of only a handful of fossils that represent very young animals.  As it was not preserved in association with a larger specimen (the mother) and as there are stomach contents present, it is likely that this fossil represents an independent, recently born animal, the first neonate Ichthyosaurus communis skeleton to be described.

The Ichthyosaurus Fossil on Display at the Lapworth Museum of Geology, University of Birmingham

The neonate Ichthyosaurus communis fossil specimen.

The neonate I. communis specimen.

Picture Credit: University of Manchester/University of Birmingham

The fossil is definitely a new born and not a dwarf species of Ichthyosaur as the scientists noted the large ring of sclerotic bone relative to the eye socket and the poorly ossified (highly cancellous) bones of the skull and other parts of the skeleton, these signs all indicate that these are the fossilised remains of a very young marine reptile.

Niche Partitioning in the Ichthyosauria

The new specimen is from the collections of the Lapworth Museum of Geology, (University of Birmingham).  Palaeontologist Nigel Larkin, a research associate at Cambridge University, cleaned and studied the specimen in 2016,  as he prepared the fossil, he became aware of its potential significance.  Nigel has recently been involved in an extensive restoration project at Biddulph Grange in Staffordshire.  He has been helping to restore the Victorian Geological Gallery at this National Trust property to its former glory.  As one of the most highly respected fossil preparators in the UK, Nigel was able to reveal the fossil’s secrets as he cleaned and helped to preserve the delicate marine reptile skeleton.

To read an article about the Geological Gallery preservation project at Biddulph Grange: Fossil Hunting at Biddulph Grange

The discovery of squid remnants in the gut area suggests these types of Ichthyosaur specialised in hunting cephalopods.  Commenting on the implications of this fossil, Dean Lomax explained:

“This is interesting because a study by other researchers on a different type of Ichthyosaur, called Stenopterygius, which is from a geologically younger age, found that the small – and therefore young – examples of that species fed exclusively on fish.  This shows a difference in prey-preference in new-born Ichthyosaurs.” 

This could hint at niche partitioning, whereby similar species use different resources within an environment to reduce direct competition and to help them co-exist.

Dean Lomax and Nigel Larkin in Front of the Jurassic Seas Exhibit (Lapworth Museum of Geology)

The neonate Ichthyosaurus fossil on display.

Dean Lomax (left) and Nigel Larkin (right) in front of the Lapworth Geological Museum exhibit.

Picture Credit: University of Manchester/University of Birmingham

How Old is the Fossil?

The specimen, part of the vertebrate fossil collection of the Lapworth Museum of Geology, (University of Birmingham), has no provenance data associated with it.  Unfortunately, there were no collection notes or other details to help the palaeontologists to identify where the fossil came from.  However, permission was granted for Nigel to remove a small portion of the matrix surrounding the fossil.  He passed this on to Ian Boomer (University of Birmingham) and Philip Copestake (Merlin Energy, Resources Ltd), so that they could analyse the rock for microscopic fossils.  Based on the types of microfossil preserved, the scientists were able to identify that this Ichthyosaur was around 199-196 million years old, (uppermost Hettangian faunal stage to lowermost Sinemurian of the Early Jurassic).

Nigel outlined the difficulties the team faced:

“Many historic Ichthyosaur specimens in museums lack any geographic or geological details and are therefore undated.  This process of looking for microfossils in their host rock might be the key to unlocking the mystery of many specimens.  Thus, this will provide researchers with lots of new information that otherwise is lost.  Of course, this requires some extensive research, but it is worth the effort.”

In addition, establishing a microfossil signature for a fossil may also help in those cases where theft of fossil material is suspected.

As part of the study, the skeleton was Micro CT-scanned and a three-dimensional digital model was created by Steve Dey of ThinkSee3D Ltd.  Using medical imaging software, Steve converted the three sets of CT cross-sectional images (from scans of the tail, middle section and head) into a single digital three-dimensional model of the whole animal.  This non-destructive technique provided further key information helping to identify the species and potentially, helping to provide new data on Ichthyosaur ontogeny.

The beautiful new-born Ichthyosaurus is on display in the recently refurbished Lapworth Museum of Geology, University of Birmingham, which was nominated for the 2017 Art Fund Museum of the Year.

The scientific paper: “The First Known Neonate Ichthyosaurus communis Skeleton: A Rediscovered Specimen from the Lower Jurassic, UK” by Lomax, D. R., Larkin, N. R., Boomer, S., Dey, S. and Copestake, published in “Historical Biology”.

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