Phylogeny of Fungi-loving Flies Being Sorted

The fossils of dinosaurs and other huge vertebrates might grab the headlines but there is an enormous volume of research dedicated to examining the fossil record of some of the less high profile, but arguably more significant prehistoric creatures.  Take for example, the recent paper put together by researchers from the National Museums of Scotland and the Smithsonian Institution that helped resolve part of the family tree of the Diptera, essentially this is the Order of flies, part of a group of winged insects that could lay claim to being amongst the most successful animals to have ever existed.

The research focused on the fossils associated with one family of flies, the Bolitophilidae.  They are tiny and common in temperate forests across the Northern Hemisphere and their larvae feed almost exclusively on mushrooms.  These little flies may not be very big, but the play a huge role in ensuring a balanced, healthy ecosystem.

A New Species of Eocene Fly Has Been Identified from Baltic Amber (Bolitophila rohdendorfi)

Picture credit: National Museums of Scotland

Little Prehistoric Animals Preserved in Baltic Amber

The earliest fossil material associated with bolitophilids comes from Baltic amber and from contemporaneous amber found in Montana (Kishenehn Formation).  The fossilised tree resin has preserved the remains of individuals that had become trapped in sticky tree resin.  These fossils date from approximately 46 million years ago (Lutetian stage of the Eocene Epoch).  The fossilised flies look remarkably like their extant relatives. They look like small crane flies but they are, in truth a form of gnat.  The remarkable specimens entombed in the amber have allowed the scientists to make detailed observations helping to clarify the taxonomy and evolutionary history of this fly family.

Two New Species of Bolitophilid Fly Erected

These well-preserved fossils have allowed the scientists to erect two new species within the Bolitophilidae family.  The specimens from Montana have been named Bolitophila warreni and the Baltic amber fossils represent Bolitophila rohdendorfi.  Perhaps more significantly, these Eocene gnats have permitted scientists to revise the phylogeny of other ancient flies.  Fossils from the Lower Cretaceous of Mongolia and Transbaikalia had been placed in the Bolitophilidae family (subfamily Mangasinae) but their taxonomic position was controversial.

Thanks to this new research, the affinity of the Mangasinae within the Bolitophilidae has been confirmed.  In addition, a review of the fossil material has enabled a further two species of the fly genus Mangas to be erected, namely Mangas kovalevi and Mangas brevisubcosta both of which originate from the Lower Cretaceous of Khasurty in Western Transbaikalia.

Beautifully Preserved Lower Cretaceous Fly (Mangas kovalevi)

Picture credit: National Museums of Scotland

Linking Lower Cretaceous Flies to Upper Cretaceous Dromaeosaurs

Dinosaurs and other prehistoric animals were plagued by flies, just like animals today. Although members of the Bolitophilidae family would have been more interested in fungi than flesh.  However, there is a further link between these flies and a member of the Dinosauria.  The dromaeosaurid named Tsaagan mangas, which was scientifically described in 2006, its trivial name was also inspired by a legendary Mongolian monster, the same legendary beast that was the inspiration behind the name of the bolitophilid subfamily, the Mangasinae and the erection of the Mangas genus.

Everything Dinosaur acknowledges the assistance of a press release from the National Museums of Scotland in the compilation of this article.

The scientific paper: “Review of the Fossil Record of Bolitophilidae, with Description of new Taxa and Discussion of Position of Mangas kovalev (Diptera: Sciaroidea)” by Dale E. Greenwalt and Vladimir A. Blagoderov published in the journal Zoo Taxa.

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Sauropods Had Fleshy Pads on Their Feet

A team of scientists led by researchers from the University of Queensland have concluded that giant, long-necked dinosaurs (Sauropoda), probably walked in a “high-heeled fashion”.  Their great weight was supported by a fleshy pad at the base of the foot, effectively cushioning the heel and helping to support their enormous weight.  Elephants also have a fleshy pad on their feet, it seems that these two types of terrestrial, giant tetrapods, although not closely related, evolved the same type of soft tissue pad supporting the elevated metatarsus, an example of convergent evolution.

An Anatomical Reconstruction of the Right Hind Foot of a Sauropod (Rhoetosaurus brownei)

Picture credit: Jay P. Nair and Andréas Jannel (University of Queensland)

Sauropod Locomotion – The Biomechanics

How the sauropod foot worked is very poorly understood.  This is partly because there are not that many complete foot fossils to study (manus and pes in these quadrupeds), especially amongst early members of the group and there is no living equivalent of these long-necked giants around today, to provide scientists with anatomical comparisons.  The researchers from the University of Queensland in collaboration with colleagues from Monash University (Victoria), examined the foot and toe bones of Rhoetosaurus brownei in a bid to plot the biomechanics of sauropod locomotion.

At around twenty tonnes and with a body length in excess of fourteen metres, Rhoetosaurus was a very sizeable animal, but certainly not the biggest of the Sauropoda.  However, it is known from eastern Australia so its fossils were easy to access for the researchers and it is the earliest representative of sauropods known from Australia.  In fact, according to the press release from the University of Queensland, it is the only named Australian sauropod that dates from the Jurassic.  Conveniently, it is the only one from the Gondwanan Middle Jurassic that preserves an articulated foot.

A Model of Rhoetosaurus (R. brownei)

Three-dimensional Modelling of a Dinosaur’s Foot

The scientists carefully analysed the foot bones and compared them to the foot bones of an African elephant (Loxodonta).   Lead author of the research, PhD student Andréas Jannel (University of Queensland), explained:

“Looking at the bones of the foot, it was clear that Rhoetosaurus walked with an elevated heel, raising the question: how was its foot able to support the immense mass of this animal, up to 40 tonnes?  Our research suggests that even though Rhoetosaurus stood on its tiptoes, the heel was cushioned by a fleshy pad.  We see a similar thing in elephant feet, but this dinosaur was at least five times as heavy as an elephant, so the forces involved are much greater.”

The researchers used physical models and computer simulations to map the posture and the range of motion of the foot bones.  The results generated permitted the team to model all the foot bone postures and from this it was deduced that some of these movements would have been restricted by soft tissue in life, but this soft tissue would have helped to support the animal’s great weight.

Studying the Sauropod Pes

The team concluded that the in‐life plantar surface of the sauropod pes is inferred to extend caudally from the digits, with a soft tissue pad supporting the elevated foot bones, in essence, these terrestrial giants walked in a “high-heeled fashion”.  Furthermore, the plantar pad is inferred to play a role in the reduction of biomechanical stresses, and to aid in support and locomotion.

A foot pad may have been a key biomechanical innovation in early sauropods, ultimately resulting in a functionally plantigrade foot, which may have arisen during the Early to Middle Jurassic.  Although, these dinosaurs, like all other dinosaurs had a digitigrade or semi-digitigrade stance, the soft tissue pad changed their feet morphologically, so, these dinosaurs had a more plantigrade stance (not just walking on their toes).

This research into the locomotion of the biggest land vertebrates that ever lived has provided some intriguing insights, but the authors of the scientific paper admit that further mechanical studies are ultimately required to permit a more complete understanding of how these giants moved about.

Studies of Sauropod Tracks and Trackways Lend Support to Idea that these Animals Walked on Pads of Soft Tissue

Picture credit: Okayama University of Science

The scientific paper: “Keep your Feet on the Ground”: Simulated Range of Motion and Hind Foot Posture of the Middle Jurassic Sauropod Rhoetosaurus brownei and its Implications for Sauropod Biology by Andréas Jannel, Jay P. Nair, Olga Panagiotopoulou, Anthony Romilio and Steven W. Salisbury published in the Journal of Morphology.

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