Wednesday, 15 May 2013

Malawania - swimming against the tide of 'informed' opinion.

Sometimes, analyses don’t give you the results you are expecting.  Sometimes that is down to human error – but at other times it is simply because the model you have in your head is wrong.

The slab as originally found, near Chia Gara, Amadia.
Take the new ichthyosaur published in Biology Letters today, Malawania anachronus.  It was discovered in 1952 by British petroleum geologists working in Iraq – walking down a mule track, they were engaged in an argument, when one of them happened to look down at the slab of rock that he was standing on.  Dragged into position to dam a small river, the block (right) contained the remains of an ichthyosaur, consisting of some skull remains, much of the postcranial skeleton, and critically including significant pectoral girdle material.  As this was the only ichthyosaur known from the Middle East, the geologists realised its importance, and brought it back with them to (what is today called) the Natural History Museum (London).  There, it came to the attention of Robert Appleby, who up to the early 1970s was the only person working on ichthyosaurs in Britain

Robert Appleby's original text figure of the 
skull region, submitted for his description.
Appleby was fascinated by the specimen – it had been recorded at the museum as Lias (Early Jurassic) in age, but he recognised it as having an archaic form, and wondered if it might actually be Late Triassic.  He started his investigations around the end of 1974, contacting members of the original survey team, in an attempt to constrain the age of the specimen, and identify which formation the slab could have come from.  Over the next 4 years, the authorities who had worked in the region told him repeatedly that the Triassic in that area was barren of fossils, and it must have come from the Jurassic Sargelu Formation.  As Appleby prepared his manuscript to submit to the journal Palaeontology in summer of 1979, he sent photographs of some isolated pollens from the block to the Cambridge palynological authority Norman Hughes, asking him if he could determine whereabouts in the Jurassic sequence the specimen could have come from.  He got an unexpected reply.

Hughes queried whether he had received the correct images, as the samples from the ichthyosaur block clearly indicated a Cretaceous (probably pre-Aptian) age. 
Some of the images of the 1979 sampled
palynomorphs that led Norman Hughes
to identify their source as undoubtedly
Early Cretaceous.
This just did not fit with what Appleby was expecting at all.  He had been told by one of the geologists that the Cretaceous beds were some distance away from the locality where the slab was found, and (in somewhat derogatory terms) that the local people simply would not have expended the effort required to transport the slab that far.  Hughes attempted a further sample from the block, but this time could only obtain organic residue.  Appleby appears to have decided that the first sample had in some way become confused, and with Hughes’ second sample proving inconclusive, abandoned further palynological attempts at dating the slab.  Instead, he tried to pursue the age of the slab based on invertebrate fossils in the area….in effect, he was becoming distracted into trying to determine the age of the local geology, rather than the slab containing the ichthyosaur.

Appleby eventually had his paper accepted for Palaeontology in the late eighties – provided he could tick one final box: resolve the age of the specimen.  Busy working on his massive monograph of the ichthyosaurs, he decided to leave the Iraq specimen (which he had planned to call Iraqisaurus kurdistanensis) until his monograph was completed.  Sadly, he died only five days after he had written the last pages, some years later, so never returned to work on the date for the Iraq ichthyosaur.

When I came across this unresolved work in his archives, I determined to try to complete the journey of this publication (and others).  The first thing that I did was take a new sample
The slab NHMUK PV R6682 in July 2007, prior to matrix being
resampled for pollen/spores/dinoflagellates.  White boots for scale.
from the slab (left) – although it first of all yielded the organic residue that Hughes had obtained, further processing by Steve Brindley and James Riding (BGS) yielded a sample whose pollen/spore assemblage perfectly matched Hughes’ assessment over thirty years earlier: Early Cretaceous (specifically, late Hauterivian-Barremian).  At this point, I approached Valentin Fischer (a specialist on Early Cretaceous ichthyosaurs) to join Darren Naish on writing duties.  Fischer was a perfect choice, as he was not only familiar with the development of literature and new specimens over the last twenty years (and the changes to our understanding of ichthyosaur relationships), but he had already seen signs that the end Jurassic extinction had not been quite so rough an experience for ichthyosaurs as had previously been thought.  As such, he was not trapped in the orthodox mindset that only a very few closely-related ichthyosaurs (all members of Ophthalmosauridae – a family Appleby was extremely familiar with) actually made it through to the Cretaceous.  It is conclusively not a member of that family (lacking all derived features), and structures of its scapula and forepaddle clearly show it to be archaic, as recovered time and again from our analyses.  It is – if you like – a fossilised ‘living fossil’: when the coelacanth was recovered off the coast of South Africa in the early twentieth century, it was thought to have been extinct for more than 70 million years.  So finding Malawania almost 70 million years after it was thought to be extinct is a similar surprise.  And just as that one specimen was incontrovertible evidence of the survivial of the coelacanth, so this single specimen is also true of the survival of Malawania’s kind.

There is a certain unity to the assessment of the specimen by Appleby, and Fischer’s work: both recognised the specimen as unusually ‘archaic’ in its morphology.  Fischer, however, was neither constrained by poor advice from local ‘experts’ on the limitations of the age, nor by a narrow view of the diversity of taxa that made it through the Jurassic-Cretaceous extinction. Not all ichthyosaur workers might find it so easy to move on with this very necessary paradigm shift, being ‘stuck in the past’ very much as Malawania’s skeletal anatomy was. 

But they will have to – because there are more specimens to come. 

At left, Malawania, the Jurassic-style Cretaceous ichthyosaur from Iraq; 
at right, fellow Jurassic extinction survivor  Acamptonectes
Illustrations by Robert Nicholls (; 
colouring by C. M. Kosemen (
Guest post by Jeff Liston, Co-Author, Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming, Yunnan Province, People’s Republic of China.

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