The Dinosaur that Went Viral: Looking at the science behind the Facebook posts

An Exceptionally Preserved Three-Dimensional Armored Dinosaur Reveals Insights into Coloration and Cretaceous Predator-Prey Dynamics

Caleb M. Brown, Donald M. Henderson, Jakob Vinther, Ian Fletcher, Ainara Sistiaga, Jorsua Herrera, Roger E. Summons

Summarized by Time Scavengers contributor, Maggie Limbeck

What data were used? The holotype specimen (fossil or other specimen that all others are compared to to determine what it is) of Borealopelta markmitchelli was used for all experiments touched on in this article. Data was also collected from other members of the Ankylosauria (armored, herbivorous dinosaurs with a club on their tail) clade for comparison.

Methods: A phylogenetic analysis (family tree) was completed using this new dino as well as others from the Ankylosauria and Nodosauridae (Ankylosaurs missing the club on their tail) clades to determine where in the dinosaur tree B. markmitchelli belongs. This also provided data for comparison in life habit and some of the unusual features of this particular dinosaur. Additionally, geochemical studies were done on this specimen, including scanning electron microscopy (SEM) and time-of-flight secondary ion mass spectroscopy (TOF-SIMS). Both of these methods were used to get an idea of what the preserved organic material on the specimen was and determine what kinds of fossil melanins (pigments) were present.

Results: The resulting phylogenetic tree from this study does place B. markmitchelli where one would expect it to go within the Ankylosauria tree (within the Nodosauridae clade). The TOF-SIMS experiment showed that there were ions present that indicate benzothiazole and therefore pheomelanin was present. These particular chemicals would indicate that parts of this dinosaur were reddish-brown in color. However, not all parts of the osteoderm (bony skin) and epidermal coverings (scales) show this reddish-brown coloration.

Figure 1. A graphical summary of the paper. We see an image of B. markmitchelli that is exceptionally preserved, the results of the mass spectroscopy experiments that told us that there is countershading (camouflage) caused by the pigment pheomelanin that gave the dinosaur a reddish brown color. This reddish-brown color is a result of strong predation pressure and an attempt to better camouflage themselves.

Why is this study important? This study is important because it highlights how much we can learn from one extremely well preserved individual fossil. It was used in a phylogenetic analysis to determine where it belongs in the dinosaur-scheme of things, images were taken of the skull, and geochemical data was returned to determine the coloration of the skin. From these studies the scientists were able to determine that these dinosaurs used camouflage to help protect them from predators. This is very different from what we see today in predator-prey interactions. Borealopelta markmitchelli was by no means a small dinosaur (~5.5m long and ~1,300kg) and had significant body armor yet it still needed camouflage. Today, large mammals comparable to this size do not need camouflage because even the fiercest predator does not go after grown adults. This new relationship between Cretaceous predator and prey highlights major differences in large predator-prey interactions through time. This specimen will continue to play a major role in research for years to come.

The big picture: There are really two big picture things to take away from this article. The first being that science, and ground breaking science in particular, is always interdisciplinary. These paleontologists relied on geology, biology, ecology, and chemistry (to name a few) to come to their conclusions about B. markmitchelli. This is really important because people always think that science is very isolating and you only work on your own, when in actuality science is accomplished by a team of people who can support you and fill in knowledge gaps. Second, it is important to look into those flashy science articles that pop up on your newfeeds and on Twitter. Those articles are press releases to get you interested in the science that is being done on these fossils or rocks or bacteria. We scientists get excited about our work and want to share it with people-take the time to do so, get excited about nature, and keep reading!

Citation: Brown et al., An Exceptionally Preserved Three-Dimensional Armored Dinosaur Reveals Insights into Coloration and Cretaceous Predator-Prey Dynamics, Current Biology (2017), DOI: 10.1016/j.cub.2017.06.071

Global risk of deadly heat

Global risk of deadly heat

Camilo Mora, Benedicted Dousset, Iain R. Caldwell, Farrah E. Powell, Rollan C. Geronimo, Coral R. Bielecki, Chelsie W. W. Counsell, Bonnie S. Dietrich, Emily T. Johnson, Leo V. Louis, Matthew P. Lucas, Marie M. McKenzie, Alessandra G. Shea, Han Tseng, Thomas W. Giambelluca, Lisa R. Leon, Ed Hawkins, and Clay Trauernicht

Data: This study was conducted by gathering data from previous studies and looking at the number of lethal heat events that have occurred around the world from 1980 to 2014. The study also estimates the percentage of the population that is at risk from increased air temperatures and humidity due to human-induced climate change in the future.

The number of days per year that different areas are exposed to deadly heat and humidity (‘threshold’). The simulations, a-d, are from models into the year 2100. A) historical data from other published studies; B) RCP 2.6 scenario where nearly all emissions are cut; C) RCP 4.5 is a scenario where most emissions are cut; D) RCP 8.5 is the ‘business as usual’ scenario where emissions are not cut at all.

Methods: The authors used data from 911 previous studies to use in their analysis. They collected information on the place and dates of lethal heat events, or extreme heat events that led to human deaths. The number of days per year that surpassed the heat threshold for which humans can live in was assessed for each year (1980-2014). To determine how much of the population may be at risk of heat-related deaths in the future, the scientists used four different CO2 scenarios to model air temperature and humidity to year 2100.

Results: From the previous studies, the scientists found 783 cases of human mortality linked to excess heat from 164 cities in 36 countries. Cases of heat-related deaths were concentrated to mid-latitude regions, with high occurrences in North America and Europe. Temperature and relative humidity of an area were both found to be factors important to identifying regions where climate conditions may become deadly, as these are related to human’s ability to regulate their body temperature. Currently, around 30% of the Earth’s population is exposed to climate conditions that are considered deadly. By the year 2100, this number is projected to increase to 48% under a CO2 scenario where emissions are drastically cut, and 74% under a CO2 scenario of increased emissions.

Why is this study important? This study highlights the health risks posed to humans due to increased heating of the Earth. Several countries and large cities, mostly concentrated at the mid latitude regions and equator, are at most risk.

The big picture: Under all emissions scenarios, whether we cut emissions drastically or keep emitting CO2 at the same rate, an increased percent of the human population will be at risk of heat-related deaths. This study emphasizes the importance of aggressive mitigation to minimize the human population’s exposure to deadly climates linked to human-induced climate change.

Citation: Mora, C., Dousset, B., Caldwell, I. R., et al., 2017. Global risk of deadly heat. Nature Climate Change, 7, 501-506. DOI: 10.1038/nclimate3322

Evolution of the Arch of the Foot

Chimpanzee and human midfoot motion during bipedal walking and the evolution of the longitudinal arch of the foot
Nicholas B. Holowka, Matthew C. O’Neill, Nathan E. Thompson, Brigitte Demes
Summarized by Time Scavengers contributor, Maggie Limbeck

What data were used? The only data that were utilized in this study were five male humans and two male chimpanzees that were recorded while walking. The scientists applied markers on the joints and other key points in the feet of both the humans and chimpanzees based on where they hypothesized to see foot motion in both species. These markers provided the data points that were analyzed in film after the experiment was completed.

Methods: 3D kinematic data (a human or chimpanzee foot in motion) was collected by recording the subjects walking at a self-selected speed for 11 meters. The researchers then selected representative steps for each subject to analyze the motion and utilization in certain regions of the foot. The data was analyzed using the packages ProAnalyst and MATLAB to calculate joint angles and estimate speed of walking. These angles were then used to determine the motion between the markers placed on the foot and understand the differences between human foot motion and chimpanzee foot motion.

Image of both a human and chimpanzee subject while walking. The dots on each foot indicate the markers that the researchers were using for data collection. The percentages on each image indicate the amount of motion in the midfoot that is being utilized during each part of taking a step.

Results: It was found that humans have a much greater range of motion along the sagittal plane (imaginary plane that divides the body into left and right sides) than chimpanzees, but the range of motion along the coronal plane (imaginary plane that divides the body into front and back) were similar in both species. While there were some great differences in motion along other planes the results state that the motion and parts of the foot involved are still activated at some point while walking, they are just activated during different parts of walking in chimpanzees and humans.

Why is this study important? This study is important because it was thought that the arch in human feet evolved to stiffen the foot while walking upright on two legs (bipedially) and that therefore chimpanzees would have a much greater motion in the midfoot than humans would while walking bipedally. This experiment rejects that idea because it was found that humans actually use a significantly greater amount of motion in the midfoot while walking than chimpanzees. This does not however, mean that at all times when walking do humans have more motion in their midfoot. The researchers broke walking into separate phases and during some of those phases the chimpanzees did have much more motion in their feet than humans; but when looking at the step as a whole, humans do have more motion than chimpanzees.

Big picture: The big picture here is that the total difference in range of motion between humans and chimpanzees is pretty small, only 4°. Therefore we can’t rely on using only midfoot joints to explain evolutionary differences between humans and chimpanzees. The authors suggest that looking further into morphology (shape) affects the function of the midfoot throughout motion. Essentially, evolution cannot always be easily explained by differences in bone shape-we must observe the action that the bones might be influencing.

Citation: Holowka, N.B., O’Neill, M.C., Thompson, N.E., Demes, B., 2017, Chimpanzee and human midfoot motion during bipedal walking and the evolution of the longitudinal arch of the foot: Journal of Human Evolution, p. 23-31.

Global warming and bleaching of coral reefs

Global warming and recurrent mass bleaching of corals

Terry P. Hughes, James T. Kerry, Mariana Alvarez-Noriega, Jorge G. Alvarez-Romero, Kristen D. Anderson, Andrew H. Baird, Russel C. Babcock, Maria Beger, David R. Bellwood, Ray Berkelmans, Tom C. Bridge, Ian R. Butler, Maria Byrne, Neal E. Cantin, Steeve Comeau, Sean R. Connolly, Graeme S. Cumming, Steven J. Dalton, Guillermo Diaz-Pulido, C. Mark Eakin, Will F. Figueira, James P. Gilmour, Hugo B. Harrison, Scott F. Heron, Andrew S. Hoey, Jean-Paul A. Hobbs, Mia O. Hoogenboom, Emma V. Kennedy, Chao-yang Kuo, Janice M. Lough, Ryan J. Lowe, Gang Liu, Malcolm T. McCulloch, Hamish A. Malcolm, Michael J. McWilliam, John M. Pandolfi, Rachel J. Pears, Morgan S. Pratchett, Verena Schoepf, Tristan Simpson, William J. Skirving, Brigitte Sommer, Gergely Torda, David R. Wachenfeld, Bette L. Willis, and Shaun K. Wilson

Data: The authors surveyed Australian coral reefs around the Australian coast using aerial photographs and underwater images to assess the amount of bleaching experienced by the reefs. They compared these images and data to sea surface temperature data from the area to determine if there was a correlation between sea surface temperature and coral reef bleaching. Learn about what coral bleaching is by clicking here.

Methods: The authors first took aerial photographs of the reefs from an airplane and helicopter, which flew about 150 meters above sea level, for 10 days in 2016. The researchers then ranked the severity of coral bleaching using a scale from 0 to 4, with 4 being the worse bleaching (over 60% of corals). To check that their scale from the aerial images was correct, the scientists also conducted underwater surveys of the same reefs. The same methods were conducted in 1998 and 2002 by other researchers, so the authors of this study compared their data to previous data. In this way, they have 3 years of coral bleaching data from the years 1998, 2002, and 2016 to see if bleaching events are becoming more common and getting worse. The scientists then compared their bleaching scale to observed sea surface temperatures in the area where the surveys were conducted to observe the relationship between temperature and coral bleaching.

A). The severity of bleaching of coral reefs around the northeast coast of Australia from 1998, 2002, and 2016. Dark green areas indicate <1% of corals bleached, light green indicates 1-10% bleaching, yellow indicates 10-30% bleaching, orange areas indicate 30-60% bleaching, and and red areas are where more than 60% of the corals are bleached. B) Patterns of heat stress during mass bleaching events in 1998, 2002, and 2016. Hotter colors indicate maximum heat exposure.

Results: Coral reef bleaching increased significantly from 1998 to 2016. Associated with the bleaching was an increase in the water temperature around the coasts of Australia where the corals are living.

A) Aerial view of a reef that is close to 100% bleached; B) Severe bleaching of an older coral mass on the northern Great Barrier Reef; C) staghorn corals that were killed by the major bleaching event in 1998; D) the same site in C, but 18 years later and the corals have not recovered; E, F) mature staghorn corals that were killed by heat stress and colonized by algae in just a few weeks time in 2016.

Why is this study important? This study is one of the first to examine a huge amount of coral reefs (1,156 in 2016 alone) to assess the effects of increased water temperature on coral bleaching. The researchers indicate that some coral species can grow back in 10-15 years, but some of the corals that are dying in the reefs are slow growers and very old. It will likely take decades for these corals to return to their former glory. This study indicates that we must take action now to save our coral reefs, not just around Australia, but around the world.

The Big Picture: By using large data sets and looking at trends of corals through time, scientists can concretely state that rising sea surface temperatures due to increased CO2 levels are causing mass coral reef bleaching events. When corals are stressed for too long, they die. Coral reefs are considered the rain forests of the sea because they are home to so many species of marine animals. Once the coral reefs begin to die, other animals will lose habitat to live in, and thus their numbers will, and are, declining. This has huge implications on the fishing industry, as people who rely on the ocean to make a living will no longer be able to catch bountiful amounts of fish that live around the reefs. In short, the effects of dying corals has far-reaching implications that will hurt the marine ecosystem, collapse the marine food chain, and affect economies.

Citation: Hughes, T. P., Kerry, J. T., Alvarez-Noriega, M., Alvarez-Romero, J. G., et al., 2016. Global warming and recurrent mass bleaching of corals. Nature, 543 (7645). DOI: 10.1038/nature21707

Switching Up the Dinosaur Family Tree

A new hypothesis of dinosaur relationships and early dinosaur evolution
M.G. Baron, D.B. Norman, and P.M. Barret
Summarized by Time Scavengers contributor, Maggie Limbeck

What data was used? This study looked at a wide range of dinosaurs and dinosauromorphs (dinosaur-like animals) including those from around the world from the Middle Triassic to Cretaceous. The data were focused on the early dinosaurs, from which there previously wasn’t a lot of focus on evolutionary studies. By studying the fossils of all of these different dinosaurs the researchers were able to find similarities and differences in their morphologies (structure, shape, function) to create a character list to be used to create a new phylogenetic hypothesis (evolutionary hypothesis) for dinosaurs.

Methods: The character list that was created by studying the fossils of the dinosaurs in question was scored for each dinosaur. This means that every dinosaur had the same questions asked about it and answered as a yes/no question. This data set was then run through TNT 1.5-beta, a phylogenetics software that generates a phylogenetic tree based on those characters. After a new tree is created based on this data it was tested for support using Bremer support (which calculates the difference between the most parsimonious tree and the next most parsimonious tree that is missing a particular clade (grouping of organisms)) and constraint trees.

Results: The major result of this study is the reorganization of the dinosaur phylogenetic tree that changes the relationships that were thought to be true since 1887. Since that time the theropods (e.g., T. rex) and sauropods (e.g., Apatosaurus and Brachiosaurus) were thought to form a group because their hips have a classic “reptilian-hip” structure while ornithischians (Triceratops) have a “bird-hip” structure. After completing this study, it was found that contrary to this belief that the groups Ornithischia and Theropoda are more closely related to each other than Saurischians and Theropoda are. Additionally, this new hypothesis of the evolutionary relationships between the major dinosaur groups helps to provide an explanation for morphological features that were previously thought to be examples of convergent evolution (similar traits shared by organisms that are not closely related) between theropods and ornithischians.

The newly hypothesized phylogenetic tree for dinosaurs. B shows the reorganization of Ornithischia (bird hipped dinos) to be most closely related to Theropoda (T. Rex style dinos). This is different than the relationship that was believed since 1887 that Theropoda and Saurischia were most closely related.

Why is this study important? This study is important because it represents a critical shift in the way that we think about and study dinosaurs. A change in the evolutionary relationship between major groups of dinosaurs will require current studies to evaluate how this change may affect their results. However, this could aid research that had unanswered questions or odd data points that may now be explained by these relationships.

Big Picture: The big picture with this study is that even things that we as scientists and science enthusiasts have thought to be true for years can be redefined. We see here that the dinosaur “family tree” has changed dramatically with just this one study. However, this paper has sparked a lot of internal fact checking and conversation that is an integral part of science that is often forgotten or hidden in the background. Many scientists have run their own phylogenetic analyses and have used different methods to decide if what these authors are claiming is, in fact, correct. All phylogenies are just hypotheses, especially with dinosaurs since we only have fossil data to use. Fossils are not always in the best shape to help us learn from them, and especially fossils from the early Triassic are lacking. By having the scientific community be so shaken by this news and running their own analyses, they are helping to strengthen the validity of this science and making it be more powerful. So while yes, this is groundbreaking science, it is also a good reminder that scientific hypotheses are still extensively tested and retested parts of science, not just a guess or a hunch.

Citation:Baron, M.G., Norman, D.B., Barret, P.M., 2017, A new hypothesis of dinosaur relationships and early dinosaur evolution: Nature, p. 501-506.

How well do stable isotopes really work?

Defining uncertainty and error in planktic foraminiferal oxygen isotope measurements

Andrew Fraass and Christopher Lowery

Summary by Andy Fraass, website collaborator

Figure 1. Two different locations in the ocean. Temperature and salinity combine to give us the δ18O values. On the left are a few planktic foraminifera in their rough depth habitats (where each species likes to hang out in the water column) (Shiebel and Hemleben, 2005). Drawings are modified from Kennett and Srinivasan (1983) and Schiebel and Hemleben (2005).

Data: Chris and I developed a model to understand how good planktic foraminiferal isotopes actually are at recording temperature, and how important it is that a scientist uses a bunch of tests to measure the isotopes, rather than just a few. There’s actually no data in a traditional sense in this paper, we went back to theory, statistics, and math.

Methods: Chris and I wrote a theoretical model. Planktic foraminifera make their shells in a certain depth (or depths) in the water, and that depth has a certain chemistry. The model allows the scientist to say that the forams are mostly growing in a certain season and at a range of depths. Then the scientist has to decide to include how well the organism records the water chemistry (technically called ‘vital effects’), if the shell has it’s chemistry altered in the sediment (diagenesis), and a few other things including if there’s a chance that a different species (with a different ecology) got mixed in.

Results: Good results from stable isotope studies come from about 15 or so shells in an analysis, but it’s very dependent on the species and what the ocean structure is like.

Why is this study important? Given all the things that could go wrong, of which the levers in the  model are a part, it’s honestly a little surprising that planktic stable isotope records give the same results. They do, which other folks have shown repeatedly. What Chris and I show here is that as long as you put in enough shells when you’re doing your analysis, then the record actually records what we think it does!

The big picture: Studying the ocean is tough, especially when we’re talking about the ocean from tens of millions of years ago. This paper helps show that despite statistical concerns some of us had with it, we’re doing a good job at recording the past.

Citation: Fraass, A. J., and C. M. Lowery (2017), Defining uncertainty and error in planktic foraminiferal oxygen isotope measurements, Paleoceanography, 32, 104–122, doi: 10.1002/2016PA003035.

References:

  • Kennett, J.P. and Srinivasan, M.S., 1983. Neogene planktonic foraminifera: a phylogenetic atlas. Hutchinson Ross.
  • Schiebel, R. and Hemleben, C., 2005. Modern planktic foraminifera. Paläontologische Zeitschrift, vol. 79(1), p.135-148.

Gigantic Otter Discovered with Implications for Otter Evolution

A new otter of giant size, Sigmogale melilutra sp. Nov. (Lutrinae: Mustelidae: Carnivora), from the latest Miocene Shuitangba site in north-eastern Yunnan, south-western China, and a total-evidence phylogeny of lutrines

Xiaoming Wang, Camille Grohé, Denise F. Su, Stuart C. White, Xueping Ji, Jay Kelley, Nina G. Jablonski, Tao Deng, Youshan You, and Xin Yang

Data: These authors found an entire skull, jaw fragments, and parts of skeletons of three new species of otter. This otter has a skull length (snout to back of head) of about 385 mm, for comparison the length of a human skull is about 200 mm.

This is the skull of the new species, Siamogale melilutra. The specimen is the holotype from Shuitangba, number ZT-10-03-064b. This is Figure 3 in the paper.
This is the skull of the new species, Siamogale melilutra. The specimen is the holotype from Shuitangba, number ZT-10-03-064b. This is Figure 3 in the paper.

Methods: They used computed tomography (CT) scanning uses special X-rays to create detailed scans. In this study, it was used in order to reconstruct the crushed skull. CT scanning allows for virtual fossils to be created, which makes manipulating and handling the fossil much easier. There is less chance to accidentally break the fossils, which can be quite delicate. The paleontologists could then critically examine the new skull and compare it to the already understood otter skull to make statements about relationships between the new species and species that have already been discovered.

Results and Importance: After reconstructing the crushed skull the authors of the study found similarities between this skull and modern beavers and otters, such as aspects of the skull and teeth, as well as other openings in the skull. There has been disagreements between paleontologists as to the placement of otters within the larger tree of life. Different studies using different methods have obtained different results. This published study provides the first total evidence (both morphology and molecular data) evolutionary history of otters. This work suggests that a certain group of otters is not actually a natural group, but rather an early representative at the origins of the European and North American otters.

This new discovery allows for a better understanding of previously found fossils by comparing these strange fragmented bone materials to other mostly complete skulls to understand relatedness. These fragments are often labeled “badger” or “otter” with little other descriptions. This specimen shares features of both the badger and otter groups, making it a very interesting organism.

The Big Picture: By better studying these evolutionary relationships, paleontologists can now use the refined otter branch on the tree of life as a framework to assess various processes. Specifically, there appears to be large implications for speciation and biogeographic (what species lived where, and why) trends in this group. The distance between certain locations of specimens discovered implies that these large otters were very good at crossing barriers (such as rivers) that often restrict movement of groups.

This is an artist’s (Mauricio Antón) reconstruction of a habitat that would have contained this large otter and some similar animals and plants for the time period. This is Figure 12 in the paper.
This is an artist’s (Mauricio Antón) reconstruction of a habitat that would have contained this large otter and some similar animals and plants for the time period. This is Figure 12 in the paper.

Citation: Xiaoming Wang, Camille Grohé, Denise F. Su, Stuart C. White, Xueping Ji, Jay Kelley, Nina G. Jablonski, Tao Deng, Youshan You, and Xin Yang (2017): A new otter of giant size, Sigmogale melilutra sp. Nov. (Lutrinae: Mustelidae: Carnivora), from the latest Miocene Shuitangba site in north-eastern Yunnan, south-western China, and a total-evidence phylogeny of lutrines. Journal of Systematic Palaeontology, DOI: 10.1080/14772019.2016.1267666