Malaria Dates Back to the Cretaceous

The disease malaria which is a mosquito-borne infectious disease of humans and other animals caused by parasitic protozoans belonging to the Plasmodium type, killed an estimated 438,000 people in 2015.  The World Health Organisation (WHO) reports that there were some 214 million cases last year and currently, this debilitating and often fatal disease accounts for 40% of all public health spending in Africa.  Although, our understanding of the parasite and its life cycle has greatly improved over the last five decades or so, fundamental questions still remain.  For example, when did the malaria vectors first evolve?  Was malaria a disease of insects that transferred to vertebrates or did this disease originate in some prehistoric land vertebrate, a dinosaur perhaps?

Studying Malaria

Writing in the scientific journal the “American Entomologist”, researcher George Poinar Junior, a specialist in palaeo-entomology, sets out new research that seeks to establish for how long malaria has been plaguing our planet.  He concludes that the origins of the disease can be traced back to the Cretaceous, a time when the Dinosauria dominated terrestrial ecosystems.  The research suggests that dinosaurs would have probably been amongst the Plasmodium parasites first vertebrate hosts.

Fossil Evidence (Biting Midge) with Evidence of Malaria Parasite Infection Preserved in Amber

One hundred million-year-old Protoculicoides biting midge containing numerous oocysts (arrow) of the malarial parasite preserved in amber.

Picture credit: Oregon State University

Fossils Preserved in Amber

The picture above shows a 100-million-year-old biting midge, preserved in amber from Myanmar (Burma).  The black arrow indicates numerous oocysts of the malarial parasite Paleohaemoproteus burmacis.

Zoologist George Poinar has specialised in studying ancient insects and other members of the Order Arthropoda.  Much of his work has focused on the study of micro-organisms preserved in fossilised tree resin (amber).  Everything Dinosaur has written a number of articles highlighting his research over the years, back in 2008 we wrote about a book co-authored by Professor Poinar that proposed the dinosaur extinction event was brought about, in part, due to disease transmission from biting ticks, mites and insects.

To read more about this: Biting Bugs Brought About the Demise of the Dinosaurs.

The Origins of Malaria

Understanding how malaria evolved and its long-term relationship with hosts can help scientists when it comes to searching for vaccines and other measures to eradicate the disease.  The fossil record such as biting insects preserved in amber can help researchers to establish a better understanding.

Professor Poinar explained:

“Scientists have argued and disagreed for a long time about how malaria evolved and how old it is.  I think the fossil evidence shows that modern malaria vectored by mosquitoes is at least 20 million years old, and earlier forms of the disease, carried by biting midges, are at least 100 million years old and probably much older.”

The modern strains of malaria are thought to have evolved much more recently, sometime between 15,000 years ago to perhaps as far back as 8 million years ago, before hominins evolved.  The modern form of malaria is carried by Anopheles mosquitoes, but Professor Poinar suggests that the ancestral forms may have been spread by other types of biting insect.

A Tertiary Mosquito Preserved in Amber with a Malarial Parasite Infection

Evidence of malaria parasite in a mosquito preserved in Dominican amber.

Picture credit: Oregon State University

The photograph above shows the preserved remains of the mid-Tertiary mosquito Culex malariager preserved in Dominican amber. Professor Poinar identified gametes inside the mosquitoes body and oocysts of the malaria parasite Plasmodium dominicana in various stages of development.  This research, conducted in 2005, provided the first fossil record of Plasmodium malaria, demonstrating that the genus was established in the Americas at least fifteen million years ago.

Implications for this Research

If Poinar and his research team have hit the nail on the head, then ancestral malaria could have been influencing terrestrial vertebrate evolution from the Cretaceous onwards.  Poinar proposes that other ancient insects such as sand flies, ticks as well as mosquitoes could have been malarial vectors.  Of all these arthropods, the biting midges are the most ancient with a fossil record dating back to the Early Cretaceous, some 140 million years ago.  This means that malaria could have had insect vectors this far back in geological time.

The professor is keen to point out that he is not claiming an ancient malaria pathogen caused the extinction of the dinosaurs, but he does suggest that diseases passed on via biting and sucking insects could have had an effect on populations that were already under considerable environmental stress.

The Professor added:

“There were catastrophic events known to have happened around that time, such as asteroid impacts and lava flows, but it’s still clear that dinosaurs declined and slowly became extinct over thousands of years, which suggests other issues must also have been at work.  Insects, microbial pathogens and vertebrate diseases were just emerging around that same time, including malaria.”

Next time you see a mosquito, consider the evolutionary history of this winged creature and the evolutionary history of the deadly vector that some of its kind carries…

New Study Suggests Reasons for the Extinction of the Ichthyosaurs

A study undertaken by an international team of scientists and published in the open access journal “Nature Communications”, concludes that the extinction of the ichthyosaurs was probably due to an inability to evolve quickly enough in combination with intense climate change.

Superbly Adapted to a Marine Environment – The Ichthyosauria

Evolving live birth (viviparity) just one adaptation to an entirely marine existence.

Picture credit: Everything Dinosaur

Studying Ichthyosaur Extinction

Widely regarded as perhaps, the best adapted of all the marine reptiles of the Mesozoic, the ichthyosaurs with their stream-lined bodies, well developed fins varied diets and their viviparity (live birth as evidenced in a number of fossil specimens), died out some twenty-eight million years or so before the end Cretaceous mass extinction that saw the end of the dinosaurs and other types of marine reptile such as the mosasaurs and the long-necked plesiosaurs.

The reason(s) for this demise have long been debated.  During the mid part of the 20th century it had been suggested that the ichthyosaurs had persisted until the end of the Cretaceous, however, most palaeontologists now agree that the very last of these “fish lizards” died out at the end of the Cenomanian faunal stage, some 93 million years ago, a time when the world was undergoing a period of dramatic climate change.

The Rise of the Mosasaurs Not to Blame

The rapid evolution and radiation of the mosasaurs during the Late Cretaceous had been proposed as a possible factor in the extinction of the ichthyosaurs.  Many academics had argued that these lizards, (Squamata), competed with the ichthyosaurs for food and other resources such as breeding grounds.  However, recent studies have indicated that the earliest large-bodied mosasauroids, animals which could have competed with the ichthyosaurs, first appear in strata laid down in the Middle Turonian stage of the Late Cretaceous some three million years after the last appearance in the fossil record of the Ichthyopterygia Order (also called the Ichthyosauria).

It is likely that the mosasaurs benefited from the absence of the ichthyosaurs and rapidly radiated to fill some of the niches once occupied by them.

The Evolution of the Mosasaurs Not Likely to be the Cause for Ichthyosaur Extinction

Ancestral Mosasaurs during the Cenomanian faunal stage were small, the first large bodied Mosasaurs did not evolve until around 90 million years ago

Picture credit: Stephanie Abramowicz (The Dinosaur Institute, Natural History Museum of Los Angeles County)

Explaining the Extinction

Lead author of the research paper, Dr Valentin Fischer (Oxford University and the University of Liège, Belgium), explained that the research team carried out an extensive analysis of the geological record of the Ichthyosaurs, combing through data that represented the last 120 million years of this Order’s evolutionary history.

He stated:

“We analysed the extinction of this crucial marine group thoroughly for the first time.  We compared the diversity of the ichthyosaurs with the geological record of global change, emphasising the dynamics of these datasets.  Ichthyosaurs were actually well diversified during the last chapter of their reign, with several species, body shapes and ecological niches present.  However, their evolution was much slower than earlier in their history.  Additionally, they were seemingly negatively affected by the profound global changes going on during the Cretaceous, as their extinction rate correlates with environmental volatility.”

Everything Dinosaur stocks a variety of marine reptile models including several replicas of ichthyosaurs: Marine Reptiles, Ichthyosaurs and Sea Monster Models.

A Perfect Storm for the Ichthyosauria

It seems that the Ichthyosauria endured a severe decline in the number of species at the beginning of the Cenomanian.  Many specialist predators of soft-bodied creatures, died out along with several “generalist” ichthyosaurs, but those ichthyosaur species that filled apex predator roles seem to have persisted until the end of this faunal stage.

A two-pronged event is suggested to have added up to the “perfect storm” for the Ichthyosauria.  At this time, the Earth’s poles were free of ice and sea levels were much higher than today.  The analysis revealed that this two-phase extinction event (Early Cenomanian and Late Cenomanian), can be associated both with reduced evolutionary rates (a failure to evolve novel body plans for a prolonged period of geological time) and dramatic climate change (strong fluctuations in sea surface temperatures and sea levels).

The International Research Team Plotted the Demise of the Ichthyosauria

Marking the demise of the Ichthyosauria.

Picture credit: Nature Communications

The two graphs above were compiled by the international research team.  The top graph shows the number of marine reptile-bearing formations recorded throughout the whole of the Cretaceous (black line), plotted against the proportion of these formations that contain ichthyosaur fossils (beige line).  The proportion of marine reptile-bearing formations yielding ichthyosaurs decreased from 84% in the Albian to 19% in the Cenomanian and to 0% in the Turonian.  The bottom graph, plots the proportion of marine reptile-bearing formations containing ichthyosaurs throughout the Cretaceous, with calculation of a 95% confidence interval.

Ichthyosauria Did Become Rarer

These graphs indicate that the extinction is not biased by a lack of fossils of ichthyosaurs, it seems that the Ichthyosauria did indeed become rarer and rarer and then disappeared from the oceans of the world, at a time when other marine reptile populations were recovering from any extinction pressures.

Dr Fischer added:

“Although the rising temperatures and sea levels evidenced in rock records throughout the world may not directly have affected ichthyosaurs, related factors such as changes in food availability, migratory routes, competitors and birthing places are all potential drivers, probably occurring in conjunction to drive ichthyosaurs to extinction.”

For models and replicas of ichthyosaurs and other prehistoric animals: CollectA Age of Dinosaurs Prehistoric Animal Models.

This new work supports a growing body of evidence suggesting that a major, global, change-driven turnover profoundly reorganised marine ecosystems at the beginning of the Late Cretaceous (Cenomanian faunal stage), giving rise to the highly peculiar and geologically brief Late Cretaceous marine world.  Ichthyosaurs disappeared in the course of this turnover, while numerous lineages of bony fishes and sharks evolved.

It is also suspected that surface levels of oxygen were depleted during the Cenomanian.  This may have impacted on the strength and vigour within food chains, with the apex predators such as those remaining types of ichthyosaur, at the top of the food chain, affected more than most.   The extinction of ichthyosaurs thus appears to be one aspect of a larger event, something the team, which includes scientists from England, Russia, Belgium and France is currently investigating.

To read a related article written by Everything Dinosaur in 2013, that looked at how fossil finds from Iraq were changing views on the evolution of the Ichthyosauria: Fossilised “Fish Lizard” Changing Views of Ichthyosaur Evolution.

Manchester University Palaeontologist Helps Build an Ichthyosaur

The fossilised remains of a large Ichthyosaurus, one of the biggest specimens of a “fish lizard” found in the British Isles, goes on display today as a new gallery opens at the Birmingham Thinktank Museum.  Providing an exciting centrepiece to the new Marine Worlds Gallery, the fossils may represent an entirely new species of ichthyosaur.

The Skull of the Warwickshire Ichthyosaurus

A wonderful conservation example, the rebuilt Ichthyosaurus skull.

Picture credit: Birmingham Thinktank

A Manchester Palaeontologist

Dean Lomax, a palaeontologist from Manchester University has been involved in the project to rebuild and put on display the 200 million-year-old predator.  The fossils were originally found in 1955 when a farmer unearthed the first evidence of this sea monster and a field team from the Birmingham Museum and Art Gallery was despatched to investigate.  The location was Fell Mill Farm, near to the small Warwickshire town of Shipston-on-Stour in the far south of the county.  There are a number of sites in Warwickshire that yield fossils from the Early Jurassic.

Extensive quarrying of clays and limestone for the cement industry has exposed Jurassic-aged sediments and very occasionally the remains of ancient marine vertebrates are found.  Unlike most of the Ichthyosaurus fossils found in Europe, the Fell Mill Farm skull specimen has been preserved in three-dimensions (most Ichthyosaur specimens, especially the skulls, are flattened and crushed during the fossilisation process).

Rebuilding the Skull Specimen

Working with expert conservator Nigel Larkin and Luanne Meehitiya (Natural Science Curator for Birmingham Museums), Dean has been able to rebuild the skull specimen and unite it with post cranial elements from the same animal that were stored within the Birmingham Museum vertebrate fossil collection.  The restored skull measures some eighty centimetres long and is thirty-three centimetres wide (at the widest part, the rear of the skull).

It is difficult to estimate just how big this Ichthyosaur was when it patrolled the shallow seas of an archipelago of islands, that were one day to become the British Isles, but it could have measured up to six metres in length.  This would have made this animal, one of the largest types of marine reptile known from Europe excavated from Lower Jurassic strata.  It may have filled an apex predator niche, feeding on cephalopods, fish and probably, smaller marine reptiles.

The Reconstructed Skeleton Ready for Display

Nigel Larkin (left), Luanne Meehitiya (centre) and Dean Lomax (right) with the Warwickshire Ichthyosaurus specimen (scale bar 10 cm)

Picture credit: Birmingham Thinktank

An Ichthyosaurus Specimen

Rebuilding the skull and the rest of the fossil material was an exceptionally tricky task.  The skull had been constructed sometime in the late 1950s and excessive amounts of glue and filler had been used to stick the bones together.  In addition, plaster and wood had been employed to help support the fossilised bones as well as to fill in the missing bone pieces.  A number of bones had been positioned in the wrong place, the orientation was inaccurate and the whole of the jaw had been set further back.

The coat of varnish, added more than six decades ago had become discoloured and was hiding a lot of the detail, so this too had to be removed.  It was Nigel’s job to carefully take the skull to pieces and, under the expert guidance of Dean, to clean and prepare the individual fragments so that they could be put together in a more anatomically correct arrangement.

Everything Dinosaur Comments

A spokesperson from Everything Dinosaur commented:

“When the skull was first put together, the scientists at the time had not got the benefit of three-dimensional CT scans, or access to a global digital database of ichthyosaur skull fossils to help in the construction process.  We tend to take technologies like email, high resolution images, on line journals and data sharing for granted these days, but back in the late fifties the fragments of bone that make up the skull were most probably pieced together using some of the 19th century line drawings of the very first ichthyosaur fossils to be described. “

For prehistoric animal models including marine reptiles: CollectA Prehistoric Life Figures.

Once the skull had been fully restored, the project team set about conserving the rest of the skeleton creating a most impressive centrepiece for the new gallery at the Birmingham Thinktank museum.  More accurate casts of missing fossils could be used to help to fill out the exhibit and the three-dimensional nature of the skull permitted the team to gain some valuable insight into the true shape of the Ichthyosaurus skull, the basioccipital bone, for example, had been preserved.

Studying the Skull of the Ichthyosaurus

This is one of four bones at the very base of the skull that surrounds the foramen magnum, the hole in the skull through which the spinal cord passes.  This bone could provide valuable information on the shape of the ichthyosaur brain.

Commenting on the research work and the way in which this fearsome reptile is being displayed at the museum, Luanne Meehitiya stated:

“One of the most fun parts of this project has been working with palaeo-artist Robert Nicholls to produce a new artistic reconstruction of the ichthyosaur, which gives us a much better impression of what the massive marine reptile must have looked like and this is displayed life-sized above the skeleton.”

The Wonderful Illustration of the Ichthyosaur in the Marine Worlds Gallery

Large teeth in the jaws indicate predation, most probably of fish and other small marine organisms.

Picture credit: Bob Nicholls @Paleocreations

Palaeontologist Dean Lomax added:

“This is a very important specimen.  It comes from a location previously unrecorded for ichthyosaurs, so this adds to our understanding of the geographical distribution of ichthyosaurs during the Early Jurassic, a time when the UK was a series of islands.”

Ichthyosaur Research

Back in February 2015, Everything Dinosaur reported on some other ichthyosaur research undertaken by Dean Lomax.  Thanks to his efforts, the first “new” species of Ichthyosaurus for 127 years was identified.

To read about this research: New Ichthyosaurus Species Honours Mary Anning.

For those wishing to learn more about the types of dinosaur that roamed the land whilst this ichthyosaur patrolled the sea, Everything Dinosaur recommends “Dinosaurs of the British Isles” by Dean Lomax and Nobumichi Tamura: Dinosaurs of the British Isles is available here.

Note

Originally thought to represent an example of Ichthyosaurus communis a study published in 2019, classified the specimen as an example of the much rarer marine reptile Protoichthyosaurus prostaxalis.