Ichthyosaurs, the incredible prehistoric marine reptiles that inhabited the Mesozoic oceans,
were an amazingly successful and diverse lineage and a significant component of the ancient
marine ecosystems they lived in for millions and millions of years.
Coexisting with the dinosaurs, ichthyosaurs actually did not survive until the very end
of the Cretaceous when the famous mass extinction happened, instead dying out around 93 million
years ago, midway through the Late Cretaceous.
Indeed, it had been thought that these reptiles were on a considerable decline once the Cretaceous
period started, with many of the different lineages of ichthyosaur not making it past
the end of the Jurassic. However, research done in the last decade is beginning to change
these ideas, with there being more evidence that various groups of ichthyosaurs actually
persevered quite far into the final period of the Mesozoic.
One such ichthyosaur that has changed our understanding of these animals’ evolution
is a species called Malawania anachronus - the ichthyosaur out of time.
Malawania was actually first brought to the attention of science quite a while ago when
a group of British petroleum geologists were at work in the Kurdistan region of Iraq in
1952. The fossil had already been excavated and was embedded in a flat slab of rock that
had been placed in a position where it was being used as part of a dam for a small river,
as well as a stepping stone that was part of a mule track crossing the water. As such,
people and mules had been walking right over this fossil for some time, but fortunately
it doesn’t seem to have been broken in any way.
Realising that this fossil was probably quite important, the geologists therefore recovered
it and donated it to the Natural History Museum in London - then still part of the British
Museum - in 1959. After its arrival in the UK, the history of research on this specimen
then got quite complicated.
Well-known ichthyosaur worker Robert Appleby, at that time based in Cardiff and really the
only person researching ichthyosaurs in Britain up until the 1970s, then studied the Malawania
specimen for many years, and even got close to publishing a paper on the animal but ultimately
it was rejected. Appleby unfortunately never managed to complete his study of the ichthyosaur
before his death in 2004.
The main issue that faced Appleby was the confusion about the reptile’s true age.
He was highly intrigued by the fact that the museum labelled the specimen as coming from
the Early Jurassic, but he noticed how archaic and more basal it looked compared to other
Jurassic ichthyosaurs, and considered the possibility that it might actually have lived
earlier, in the Late Triassic.
Making contact with the geologists who had worked in the region, Appleby was advised
that the specimen could not be Triassic in age and must have been a Jurassic animal,
since the Triassic rocks in that area were lacking in fossils.
But Appleby continued to investigate the age of this organism, sending off photos of pollen
grains from the slab of rock the ichthyosaur was in to an expert on palynology - the study
of tiny particles such as pollen - at Cambridge.
This palynologist soon informed Appleby that the pollen grains were in fact undoubtedly
forms that came from the Early Cretaceous, not the Jurassic as he had been repeatedly
told by the geologists he was in communication with. Wanting to check if this palynological
analysis had been correct, another sample was taken from the rock and examined, but
all it turned up was organic residue - nothing conclusive.
Abandoning the palynological approach, Abbleby then started trying to find the age of the
block of rock by investigating the stratigraphy of the invertebrate fossils that had been
found in the area. By the late 80s his paper on this ichthyosaur was close to being accepted
for publication in the journal Palaeontology, but the reviewers insisted that in order to
publish he must determine the true age of the fossil.
Appleby, however, was preoccupied with a vast amount of other work on ichthyosaurs, and
as such decided to concentrate on that before returning to this age problem. Sadly, though,
he died before he could ever finish his work on Malawania.
Then, in 2013, a team of researchers managed to finish his study for him.
This group of palaeontologists was able to finally, properly determine the age of this
ichthyosaur, by taking new samples from the rock and finding a wide range of different
microfossils contained within it. These fossils demonstrated that the original palynological
analysis performed decades prior had indeed been correct - this was an Early Cretaceous-aged
ichthyosaur, despite its very archaic anatomy.
These palaeontologists therefore gave it the name Malawania anachronus - from Malawan,
the Kurdish word for ‘swimmer’, and the Latinised Greek word anachronus, meaning ‘out
of time’.
The specimen itself preserves a decent amount of the reptile’s anatomy. A fragmentary
skull is present, comprising the bony sclerotic rings of the eyes, as well as bits of a few
other skull bones, but the body is more complete. Neck and upper back vertebrae are preserved,
in addition to ribs, parts of one of the shoulder girdles, and almost all of the left forefin.
This might not seem like an awful lot, but it’s still enough to tell a great deal about
this ichthyosaur’s anatomy. And what’s very clear from the bones is that this reptile
was certainly very archaic in its features, with the scapula and bones of the forefin,
as well as others, being very characteristic of much earlier ichthyosaur lineages.
As such, the 2013 paper concludes that Malawania was actually the sister taxon to the genus
Ichthyosaurus itself, based on the phylogenetic analysis they ran. Since Ichthyosaurus live
in the Early Jurassic, this indicates that a ghost lineage - a gap in the fossil record
- of about 70 million years must exist for this branch of ichthyosaur.
The important thing here is that Malawania was found to absolutely not be a member of
the ichthyosaur family called Ophthalmosauridae, which before the description of this species
was thought to have been the only ichthyosaur lineage to survive into the Cretaceous period.
The ophthalmosaurids seem to have undergone a radiation during the Cretaceous and new
species were actually appearing quite quickly at this time, resulting in a global colonisation
by this group.
The difference in forefin anatomy between Cretaceous ophthalmosaurids and their relatives
in the Early Jurassic also demonstrates the significant morphological evolution that these
reptiles experienced as they became more and more specialised for swimming more efficiently.
Meanwhile, the lineage that Malawania was a member of was remarkably conservative in
terms of its anatomy and suggests that this group experienced a long period of evolutionary
stasis. The paper explains how some unusual events may have affected the evolution of
these particular marine reptiles, resulting in the lineage not fitting the pattern seen
in the ophthalmosaurids and remaining relatively rare in comparison.
Some ideas for this very different evolutionary history have been suggested, such as perhaps
the Malawania lineage was more specialised for inhabiting lagoons and managed to survive
by taking refuge in partially enclosed marine basins such as those that appear to have been
present in Iraq at this time in Earth’s history. But, until more information about
this mysterious relict ichthyosaur group is discovered, this remains speculation.
Importantly, though, Malawania indicates that a lot of what we understood about the reign
of the ichthyosaurs during the final period of the Mesozoic was wrong. It wasn’t just
a single branch - the ophthalmosaurids - that survived the Jurassic, it was actually at
least two. And if Malawania’s lineage made it through, it also opens up the possibility
that others did as well. But again, for now that’s complete speculation.
It will be interesting to see if more members of the Malawania lineage are discovered in
the future, perhaps helping to fill in the immense ghost lineage that currently exists.
Malawania is certainly a fascinating animal with some incredibly significant implications
for its entire order’s evolution, and I think it deserves to be better known. Indeed,
the remarkable work of the man who first studied this organism as well as many other of these
amazing marine reptiles - Robert Appleby - deserves more appreciation too, and I hope this video
helps with that.
Anyway, thank you so much for watching this video, I really hope you enjoyed it and learned
something new.