A white-tail deer has been caught on camera eating human remains.

The remains were part of a taphonomic experiment at the Forensic Anthropology Research Facility (FARF) in Texas, USA, where they were studying what types of scavengers visit human carcasses. They were left uncovered with cameras photographing anything that came to scavenge them. Imagine being the person reviewing those images, expecting to see coyotes, or racoons, or turkey vultures, and instead uncovering the first recorded instance of human bone-munching deer.

​This is not the first case of a classically herbivorous (plant-eating) animal eating bones from rotting carcasses--a behaviour called osteophagy--but it is the first time a deer has been captured nibbling on human remains.

Herbivorous animals practice osteophagy when they need more phosphate, calcium, and other nutrients in their diet. Porcupines, giraffes, cows, and even tortoises have been seen chewing on bones, most often already dry and easily accessible bones like ribs.

When recording traces of tooth-marks on bones in the modern, archaeological, or palaeontological record, it is important to remember that not all scavengers that interact with carcasses are trying to consume flesh. And that while carnivorous scavengers typically eat soft tissue and fresh bone leaving behind puncture holes and pits, bone-eating herbivores chew on the ends of older bones with teeth normally used to eat plants leaving behind long scores and forked splinters.

References
Meckel, L. A., McDaneld, C. P., Wescott, D. J., 2017. White-tailed Deer as a Taphonomic Agent: Photographic Evidence of White-tailed Deer Gnawing on Human Bone. DOI: 10.1111/1556-4029.13514.

Warm, dark-brown, sticky tar oozes out of the ground at Rancho La Brea in California, creating deep lakes of asphalt belching forth bubbles of methane. These asphalt lakes, or tar seeps, are particularly hazardous to animals passing by, trapping and swallowing up carcasses whole. And the tar seeps at La Brea have been trapping animals and luring predators to their deaths for 50, 000 years.

Rancho La Brea has produced around 3 million Pleistocene and Holocene fossils belonging to hundreds of vertebrate, invertebrae, and plant species, including dire wolves, sabertooth cats, mammoths, ground sloths, hawks, geese, owls, snakes, frogs, scorpions, spiders, ants, beetles, poison oak, juniper, red cedar, and thistle. The majority of fossils belong to mammalian predators that probably attempted to eat rotting carcasses stuck in tar, then found themselves similarly stuck in the asphalt ooze, then died and decayed thus becoming new lures for passing predators and scavengers. But no-one is quite sure how long decay might take before the carcass becomes a less appetising jumble of asphalt-soaked bones, and if those bones separate from each other and are pushed along by currents while floating at the surface, or disarticulate after sinking to the bottom of the tar seep.

A new paper by Brown et al. (2017) explores these questions by using actualistic taphonomic experiments. The authors took limbs from carcasses of a modern mammalian predator, the bobcat (Lynx rufus), and placed them in wire cages that were then lowered into tar seeps in Chivo Canyon, California. Over 10 weeks, they removed a limb from the tar seep every 2 weeks and noted how much soft tissue had decayed, as well as the types of microbes feeding on the flesh and living in the tar.

​They found that decay occurred surprisingly quickly and surmised that a rich bacterial community exists in the tar seep, ready and waiting to consume flesh. Their microbial tests showed the bacteria did not hitch-hike into the tar seep on the bobcat carcasses. We know that hundreds of petroleum-eating bacteria species already exist in the tar seeps - they produce the methane bubbles - but it now seems that there are bacteria living in these tar seeps that specialise in eating organic material.

The authors conclude that modern bobcat limbs take around 2-3 months to fully decay in tar seeps. It appears that without the presence of the experimental wire cage, their bones would disarticulate (separate) after only a few weeks. The authors propose that the majority of decay and disarticulation therefore occurs at or just below the surface of tar seep, with single bones then being buoyed along by wind or water currents. The authors admitted that while these smaller limbs portions immediately sank into the tar, larger bodies may float at the surface while decaying with parts of the body exposed to the elements, and plan to conduct more actualistic experiments using whole carcasses in the future. I'd like to see more data on the temperatures of the tar seep, and how that might speed up or slow down decay depending on the types of bacteria present. Overall, this is a very thoughtful and interesting paper, so check it out (if you can get past the paywall).

Brown, C., Curd, E., Friscia, A. 2017. An actualistic experiment to determine skeletonization and disarticulation in the La Brea tar seeps. PALAIOS, 32:119-124.

This crisp and dynamic illustration of a Protoceratops is one of the featured dinosaurs from the Institute for the Study of Mongolian Dinosaurs (ISMD), established by palaeontologist Bolortsetseg Minjin (who has been instrumental in repatriating fossils stolen from the Gobi Desert for auction in the USA).

Two weeks ago, a group of scientists started chatting on Twitter about carnivores and their prey, and started sharing gory pictures of carcasses. Things got a little (lightheartedly) competitive, and after Julien Fattebert shared a photo of a leopard cub killed by lions, and added the hashtag #bestcarcass, a Twitter battle was born.

Since then, Twitter users have shared fascinating, strange, and sometimes disturbing images of decaying animals from all over the world in weird and wonderful poses.

Listed below are my top 10 picks (in no particular order) for some of the most taphonomically interesting #bestcarcass contenders. And, unsurprisingly, some people may find the follow images disturbing: click 'read more' at your own peril...

Geology is an important component of any taphonomic investigation. This helps to 'set the scene' when considering potential taphonomic pathways: what environment did these ancient creatures live in? What happened to their bodies after they died? What environment were they buried in, and how quickly were they buried?

To this end, my colleagues and I have just published a paper about the ancient environment of the Winton Formation at Isisford to better understand the taphonomic history of crocodyliforms, osteichthyan fish, and dinosaur fossils uncovered there. We propose that around 100 million years ago, Isisford lay in the middle of a river delta that flowed into the nearby Eromanga Sea. 

We came to this conclusion by studying the sandstone concretions that encase each of the fossils found at Isisford. These concretions formed when sand grains were cemented together with calcium carbonate (calcite) from calcium-rich groundwater. The majority of fossils appear not to be distorted or warped in any way, and as fossilisation occurs under high temperature and high pressure, it seems the concretions surrounding the buried bones and afforded them some protection. If this calcite cement, and therefore the concretions formed before fossilisation, then information about groundwater quality where the bones were buried would be locked away in the calcite minerals themselves - specifically, isotopes of carbon and oxygen. 

​We tested the carbon and oxygen stable isotopic values of the calcite cement, and by comparing our results to what is ‘typical’ for fresh water and sea water, found that it formed in a brackish water environment. This wasn’t terribly surprising: the regional geology indicates that the Eromanga Sea was nearby Isisford at this time, but until now we hadn't known whether it affected the environment at Isisford or not. When we examined geological core logs from near Isisford, and compared it to the types of rocks we found at the site, we concluded that these animals were buried in a river delta that flowed into the sea, with fresh river water mixing with salty ocean water. Unfortunately, there aren’t large exposures of Winton Formation at the site that would allow for typical facies analysis, but we worked with the material we had and came up with some pretty solid conclusions.

Our next question is: if these animal's carcasses were buried in a river delta, did they die there or were their bodies washed in from far away? Did they even live nearby at all? That is the subject of future papers that we will be publishing mid to late next year.

References
Syme, C., Welsh, K., Roberts, E., and Salisbury, S. 2016. Depositional environment of the Lower Cretaceous (upper Albian) Winton Formation at Isisford, central-western Queensland, inferred from sandstone concretions. Journal of Sedimentary Research, 86: 1067-1082. DOI: 10.2110/jsr.2016.67

​The powerful bite of a crocodile can cut through flesh and bone. Their teeth puncture, scratch, scrape and crush the skeletons of their prey. They leave behind tooth marks etched into bone, taphonomic traces which have been identified in the fossil record, and can tell us about the feeding behaviours and morphologies of ancient crocodylians. Or so we thought.

A new study by Drumheller et al. (2016) found that crocodile bite marks on bones do not seem to differ between crocodiles young and old, or male and female, or long-snouted and short-snouted. They collected bones bitten by 21 species of modern crocodylians and studied the types of bite marks left on bones surfaces – whether they were pits, punctures, scores, or furrows, and whether these marks were bisected (with extra notches or scoring from serrated teeth) or hooked (marks that changed direction). They compared the types and shapes of these bite marks to the snout shape, size, sex, age, feeding behaviour (the famous ‘death roll’), and captive or wild status of each individual crocodylian that created them. They found no significant difference between the shape of the bite marks and the individual who made them – even for crocodylians of different ages, with different snout shapes, or different feeding behaviours!

However, they did determine that bisected bite marks – those showing extra notches or scoring – were indicative of the teeth of crown Crocodylia. And as bisected bite marks have been found on fossil bones, the culprits can be successfully identified as a crocodylian (or perhaps a non-crocodylian crocodyliform – that is, animals not related to modern crocodylians, but instead an ancient offshoot of crocodyliforms that are now extinct). But not every individual crocodylian creates bisected bite-marks every time they feed, depending on whether their teeth are freshly erupted and sharply serrated, or old and worn down.
​
So, it seems you might be able to identify a crown Crocodylian as the culprit of a bone bite-mark, but cannot predict its age, sex, snout shape, or which method it chose to dispatch of its prey.  

References
​
Drumheller, Stephanie K., and Brochu, Chris A. 2016. Phylogenetic taphonomy: a statistical and phylogenetic approach for exploring taphonomic patterns in the fossil record using crocodylians. PALAIOS, 31: 463-478. [Paywalled]

Soapbox Science is coming to Australia for the first time!

As a part of National Science Week 2016, Soapbox Science will take place in Brisbane where leading female researchers will talk about their scientific projects and why they love science.

Soapbox Science is a public speaking and outreach event aimed at encouraging girls and women to take up careers in science. You can hear all about why these scientists love their jobs, ask questions about their research, and see that women belong in the sciences just as much as men do.    

I will be speaking at this years Soapbox Science event at King George Square in Brisbane, on the 20th August between 1-4 pm. My talk title (coming as no surprise to long time readers of this blog) is: “Fossil forensics: how taphonomy helps us understand the death and decay of dinosaurs”. Keep an eye out for updates between now and August!

New feathery evidence for North American dinosaurs: it appears that Ornithomimus was covered with feathers everywhere except for its lower legs.

What interested me about this paper by van der Reest et al (2015) was the lack of leg feathers found.

Why?

If this feathery absence isn't taphonomic (i.e. leg feathers were present in life, but not preserved with the fossil), then perhaps their absence paves the way for another type of leg covering... perhaps, podotheca?

I've written about podotheca - the scales on the lower leg and foot seen in modern birds and reptiles - a couple of times on this blog (both on hypothesised podotheca in a coelurosaurian theropod fossil, and preserved podotheca impressions with a non-coelurosaurian theropod fossil).

In those prior studies, podotheca were proposed to be present in not only the lineage that led to modern day birds (coelurosaurs), but also theropod lineages that do not include modern birds (non-coelurosaurs). As Ornithomimus is a coelurosaur, the presence of podotheca would at least bolster the idea that this feature was present in the ancestors of modern birds.

The study by van der Reest et al (2015) doesn't hypothesise about whether there was a podotheca-like covering on the hind limbs of Ornithomimus. But it does point out the presence of both feathers across the body and skin webs attached to the upper leg, which are features also seen in modern day birds.

They do, however, suggest that the lack of feathers on the lower legs may be related to thermoregulation - a way for the animal to keep cool - which has been noted as the reason why modern ostriches, emus, and cassowaries have sparse or no leg and neck plumage.

If Ornithomimus did have podotheca on its hind limbs, the artist's reconstruction in the paper, and shown above, indicates what it would have looked like in life. In any case, let's hope for more solid evidence of podotheca in future Ornithomimus specimens.
​

References
van der Reest, A. J., Wolfe, A. P., Currie, P. J. 2015. A densely feathered ornithomimid (Dinosauria: Theropoda) from the Upper Cretaceous Dinosaur Park Formation, Alberta, Canada. Cretaceous Research, 58: 108–117.

Here's what has been making headlines this week (28th September - 4th October):

New experiments prove that colour can be fossilised
Colour preservation has been found in fossil feathers before (in the form of structures called melanosomes), but this is the first time they have been shown to potentially preserve in other soft tissues. The journal paper can be found here (paywalled).

Dinosaurs with little heads and giant bodies: why did sauropods get so big?
Being gigantic has its advantages: you're harder to eat, tend to live longer, and can regulate internal body temperature with much more ease. But if you grow a gigantically long neck, you can't have a gigantic head attached at the end.

Palaeolatitude calculator - how far has your continent drifted?
If you travelled back in time, but moved with the land your currently standing on (thanks continental drift!), where would you end up? Click anywhere on the map, and you can how far that location has moved over the course of 200 million years! The journal paper backing this up can be found here (open access).

Maiasaura life history determined from 50 slices of bone, the largest study of its kind
​A new study of Maiasaura, the "good mother lizard", indicates they grew to 2.3 tonnes over eight years, reached sexual maturity in its third year, and had similar bone structure to modern large warm-blooded mammals. The researchers plan to learn even more about Maiasaura over the coming years thanks to 'The Maiasaura Life History Project'. The journal paper can be found here (paywalled).

A key tenant of palaeontology is that soft tissue and DNA cannot be preserved in fossil bones; they’re much too old, and any soft tissue that survived microbial decay (the skin of mummies, for example) would have been mineralised. This is why, sadly, we cannot ever clone a dinosaur. But how long does it take soft tissue to decay? And more specifically, how long does blood last in the bones of a dead animal?

A new paper has just been published on the taphonomy of blood in decomposing human bones (Cappella et al., 2015). In it, the authors collected human bone samples from ‘fresh’ cadavers (no more than 24 hrs post-mortem), from those same cadavers each week for the next 7 weeks, from a ’putrified’ carcass (48-72 hours post-mortem), from 20 year old bones, and one sample from a 400 year old bone. One ‘fresh’ cadaver also had bone samples taken and frozen, boiled, or macerated (placed in fresh water). These bone samples were then examined in thin section under a microscope to see if any trace of blood could be found.

The authors found that they could identify blood in the ‘fresh’ bone, but it was nearly impossible to identify red blood cells in bones older than 2 weeks post-mortem. They confirmed that boiling and macerating bone is a very efficient ‘cleaning’ method with very little blood remaining, whereas blood was preserved well and easy to observe in frozen bone. Some more refined analysis (using immunohistochemistry) made it possible to identify red blood cells older bone samples (up to 15-20 years post-mortem), yet the amounts present were very small - found in only 10% of the bone pore space. However, no red blood cells could be detected in the 400 year old bone either by microscopy or immunohistochemistry.

The authors suggest that those who have reported seeing soft tissue in fossil bones are most likely mistaken in their interpretation. This finding is especially pertinent to palaeontology, as Schweitzer et al (2007) claimed to have found soft tissue preserved in 65 mya Triceratops horridus bone (MOR 699), 68-65 mya Tyrannosaurus rex bone (MOR 1125, MOR 555, FMNH-PR-2081), and 78 mya Brachylophosaurus canadensis bone (MOR 794). Given the results of this latest study by Cappella et al. (2015), these interpretations of dinosaur soft tissue preservation appear to be highly unlikely.

References

Cappella, A., Bertoglio, B., Castoldi, E., Maderna, E., Di Giancamillo, A., Domeneghini, C., Andreola, S., Cattaneo, C. 2015. The taphonomy of blood components in decomposing bone and its relevance to physical anthropology. American Journal of Physical Anthropology, doi: 10.1002/ajpa.22830.

Schweitzer, M. H., Wittmeyer, J. L., Horner, J. R. 2007. Soft tissue and cellular preservation in vertebrate skeletal elements from the Cretaceous to the present. Proceedings of the Royal Society B: Biological Sciences. 274 (1607):183-197. doi:10.1098/rspb.2006.3705. 274:183–197.