The Transjurane Highway Dinosaur Tracksites and Their Significance and Application for Ichnological Studies of Dinosaur Palaeobiology

As has been unanimously commented upon in previous expert reports (Lockley, 2009; Bates, 2010; Hutchinson, 2010; Stevens, 2010), the dinosaur tracksites of the Transjurane Highway represent an incredible scientific and cultural resource. Having been fortunate enough to spend time visiting the tracksites during September 2010, in particular the Courtedoux—Béchat Bovais and Courtedoux—Sur Combe Ronde tracksites, we were able to see firsthand the extent to which this is overwhelmingly the case. What makes the tracksites globally unique is twofold. Firstly, it is the fossils themselves, of which the sheer number alone is of great consequence, enabling statistical studies into track variation both between and within individual trackways. Even regardless of the abundance of tracks, their preservation is also of great interest to palaeontologists and sedimentologists. Secondly, it is not only the tracks themselves that warrant such praise, but also the methods of documentation that have been carried out as part of the ongoing Palaeontology A16 Project. The methodical collection of data combining traditional ichnological techniques with modern documentation technologies such as high resolution laser scanning and photogrammetry, as well as the collection of specimens and the production of casts has lead to an ichnological research resource that is internationally unparalleled in terms of volume of data and potential accessibility of that data. However, as noted by Hutchinson (2010), documentation, scientific research, and subsequent publication must occur together, for data collection is nothing without published scientific findings, and as expressed by Stevens (2010), the monumental task of carrying out documentation and research simultaneously demands that such work be undertaken collaboratively in order to maximise efficiency. This report aims to present possible research projects that combine the extraordinary data collected by the Palaeontology A16 Project with recent advances in virtual ichnological methods with the hope of producing high impact publications that will become not only a part of global dinosaur track research, but integral to a wide range of palaeobiological studies concerning palaeo(bio)geography, biomechanics, palaeoenvironment and substrate mechanics. It is also important to make data and results accessible, not only to other researchers who can then advance the science further, but to the public as well, in order to educate and inspire future generations of scientists. The remainder of this report is divided into three sections. The first of these sections will outline possible research projects including hypotheses, general methodologies, and the expected time taken to complete the research. The second part will look at how the data and research can be used to both engage with the public and be made more accessible to other researchers. Finally, the third section will discuss the challenges and technical aspects of working with such a volume of digital data as has been, and is currently being, collected by the Palaeontology A16 Project

Low cost 3D scanning using off-the-shelf video gaming peripherals

Digitization of specimens is becoming an ever more important part of palaeontology, both for archival and research purposes. The advent of mainstream hardware containing depth sensors and RGB cameras, used primarily for interacting with video games, in conjunction with an open platform used by developers, has led to an abundance of highly affordable technology with which to digitize specimens. Here, the Microsoft® Kinect™ is used to digitize specimens of varying sizes in order to demonstrate the potential applications of the technology to palaeontologists. The resulting digital models are compared with models produced using photogrammetry. Although the Kinect™ generally records morphology at a lower resolution, and thus captures less detail than photogrammetric techniques, it offers advantages in speed of data acquisition, and generation of a completed mesh in real time at the point of data collection. Whilst it is therefore limited in archival applications, the ease of use and low cost, driven by strong market competition, make this technology an enticing alternative for studies where rapid digitization of general morphology is desired

Mitigating the Goldilocks effect: the effects of different substrate models on track formation potential

In ichnology, the Goldilocks effect describes a scenario in which a substrate must be ‘just right’ in order for tracks to form—too soft, the animal will be unable to traverse the area, and too firm, the substrate will not deform. Any given substrate can therefore only preserve a range of tracks from those animals which exert an underfoot pressure at approximately the yield strength of the sediment. However, rarely are substrates vertically homogeneous for any great depth, varying either due to heterogeneity across sediment layers, or from mechanical behaviour such as strain hardening. Here, we explore the specificity of the Goldilocks effect in a number of virtual substrates simulated using finite- element analysis. We find that the inclusion of strain hardening into the model increases the potential range of trackmaker sizes somewhat, compared with a simple elastic–perfectly plastic model. The simulation of a vertically heterogeneous, strain hardening substrate showed a much larger range of potential trackmakers than strain hardening alone. We therefore show that the Goldilocks effect is lessened to varying degrees by the inclusion of more realistic soil parameters, though there still remains an upper and lower limit to the size of trackmaker able to traverse the area while leaving footprints

Tracks made by swimming Hippopotami: An example from Koobi Fora (Turkana Basin, Kenya)

Here we report an ichnological surface close to Koobi Fora, Kenya in palaeontological collecting Area 103. The surface is marked by hominin tracks, as well as many traces from large animals. A southern excavation of the surface some 70 m from the hominin tracks displays a diverse range of animal track typologies, most of which appear to have been made by a four digit animal moving via punting or bottom walking in a shallow water body. Due to the track morphology and the associated fossil record, the non-hominin tracks are interpreted as being made by hippopotami, potentially including pygmy species or juveniles. The track typologies are explained using modern analogue observations of hippopotami sub-aquatic locomotion. This work provides important environmental context for adjacent hominin tracks and fossils, as well as providing the first recorded description of fossilized swim tracks made by mammals. The site has implications for the interpretation of swim tracks in the geological record particularly the widespread and controversial tracks made by sauropods and other dinosaurs

The extinct, giant giraffid Sivatherium giganteum – skeletal reconstruction and body mass estimation

Sivatherium giganteum is an extinct giraffid from the Plio–Pleistocene boundary of the Himalayan foothills. To date, there has been no rigorous skeletal reconstruction of this unusual mammal. Historical and contemporary accounts anecdotally state that Sivatherium rivalled the African elephant in terms of its body mass, but this statement has never been tested. Here, we present a three-dimensional composite skeletal reconstruction and calculate a representative body mass estimate for this species using a volumetric method. We find that the estimated adult body mass of 1246 kg (857—1812 kg range) does not approach that of an African elephant, but confirms that Sivatherium was certainly a large giraffid, and may have been the largest ruminant mammal that has ever existed. We contrast this volumetric estimate with a bivariate scaling estimate derived from Sivatherium's humeral circumference and find that there is a discrepancy between the two. The difference implies that the humeral circumference of Sivatherium is greater than expected for an animal of this size, and we speculate this may be linked to a cranial shift in centre of mass

Cambrian cinctan echinoderms shed light on feeding in the ancestral deuterostome

Reconstructing the feeding mode of the latest common ancestor of deuterostomes is key to elucidating the early evolution of feeding in chordates and allied phyla; however, it is debated whether the ancestral deuterostome was a tentaculate feeder or a pharyngeal filter feeder. To address this, we evaluated the hydrodynamics of feeding in a group of fossil stem-group echinoderms (cinctans) using computational fluid dynamics. We simulated water flow past three-dimensional digital models of a Cambrian fossil cinctan in a range of possible life positions, adopting both passive tentacular feeding and active pharyngeal filter feeding. The results demonstrate that an orientation with the mouth facing downstream of the current was optimal for drag and lift reduction. Moreover, they show that there was almost no flow to the mouth and associated marginal groove under simulations of passive feeding, whereas considerable flow towards the animal was observed for active feeding, which would have enhanced the transport of suspended particles to the mouth. This strongly suggests that cinctans were active pharyngeal filter feeders, like modern enteropneust hemichordates and urochordates, indicating that the ancestral deuterostome employed a similar feeding strategy

Digit-only sauropod pes trackways from China - evidence of swimming or a preservational phenomenon?

For more than 70 years unusual sauropod trackways have played a pivotal role in debates about the swimming ability of sauropods. Most claims that sauropods could swim have been based on manus-only or manus-dominated trackways. However none of these incomplete trackways has been entirely convincing, and most have proved to be taphonomic artifacts, either undertracks or the result of differential depth of penetration of manus and pes tracks, but otherwise showed the typical pattern of normal walking trackways. Here we report an assemblage of unusual sauropod tracks from the Lower Cretaceous Hekou Group of Gansu Province, northern China, characterized by the preservation of only the pes claw traces, that we interpret as having been left by walking, not buoyant or swimming, individuals. They are interpreted as the result of animals moving on a soft mud-silt substrate, projecting their claws deeply to register their traces on an underlying sand layer where they gained more grip during progression. Other sauropod walking trackways on the same surface with both pes and manus traces preserved, were probably left earlier on relatively firm substrates that predated the deposition of soft mud and silt . Presently, there is no convincing evidence of swimming sauropods from their trackways, which is not to say that sauropods did not swim at all

Downsizing a giant: Re-evaluating Dreadnoughtus body mass

Estimates of body mass often represent the founding assumption on which biomechanical and macroevolutionary hypotheses are based. Recently, a scaling equation was applied to a newly discovered titanosaurian sauropod dinosaur (Dreadnoughtus), yielding a 59 300 kg body mass estimate for this animal. Herein, we use a modelling approach to examine the plausibility of this mass estimate for Dreadnoughtus. We find that 59 300 kg for Dreadnoughtus is highly implausible and demonstrate that masses above 40 000 kg require high body densities and expansions of soft tissue volume outside the skeleton several times greater than found in living quadrupedal mammals. Similar results from a small sample of other archosaurs suggests that lower-end mass estimates derived from scaling equations are most plausible for Dreadnoughtus, based on existing volumetric and density data from extant animals. Although volumetric models appear to more tightly constrain dinosaur body mass, there remains a clear need to further support these models with more exhaustive data from living animals. The relative and absolute discrepancies in mass predictions between volumetric models and scaling equations also indicate a need to systematically compare predictions across a wide size and taxonomic range to better inform studies of dinosaur body size

3D morphology of nematode encapsulation in snail shells, revealed by micro-CT imaging

Many parasites and hosts are embroiled in an on-going arms race that affects the evolution of each participant. One such battle is between parasitic nematodes and terrestrial gastropods which have co-evolved for 90-130 MY. Recently, snails have been shown to encase and kill invading nematodes using their shell as a defence mechanism. However, there is remarkably little known about this process in terms of understanding where, when and how nematodes are fixed within the shell. Also there has never been any attempt to observe this process using methods other than light microscopy. Therefore, we used micro CT scanning of a Cepaea nemoralis shell (a common host for nematodes) to 3D visualise encased nematode parasites and quantify morphological parameters. By taking this approach future studies could use micro CT scanning of fossil shells in conchology collections to understand nematode/snail co-evolutio

Constructing and testing hypotheses of dinosaur foot motions from fossil tracks using digitization and simulation

Whilst bones present a static view of extinct animals, fossil footprints are a direct record of the activity and motion of the track maker. Deep footprints are a particularly good record of foot motion. Such footprints rarely look like the feet that made them; the sediment being heavily disturbed by the foot motion. Because of this, such tracks are often overlooked or dismissed in preference for more foot‐like impressions. However, the deeper the foot penetrates the substrate, the more motion is captured in the sediment volume. We have used deep, penetrative, Jurassic dinosaur tracks which have been naturally split into layers, to reconstruct foot motions of animals living over 200 million years ago. We consider these reconstructions to be hypotheses of motion. To test these hypotheses, we use the Discrete Element Method, in which individual particles of substrate are simulated in response to a penetrating foot model. Simulations that produce virtual tracks morphologically similar to the fossils lend support to the motion being plausible, while simulations that result in very different final tracks serve to reject the hypothesis of motion and help generate a new hypothesis