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I’ve Got Your Missing Links Right Here (13 February 2016)


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Top picks:

From me at the Atlantic:

NASA has built a rock collection so its rovers can practice punching holes in Mars. Wonderful Nadia Drake story.

Sad story about the genuine harm that terrible press releases can inflict on vulnerable people. By Ivan Oransky

Is Toxoplasma driving chimps towards leopards? By Carl Zimmer

These Scientists Saw Zika Coming. Now They’re Fighting Back. Superb colourful reporting by Sarah Zhang

“Scientists have identified neural pathways that react almost exclusively to the sound of music — any music.” By Natalie Angier

You can train your body into thinking it’s had medicine. Two amazing stories from Jo Marchant.

Another tragedy of sexual harassment, this time in anthropology. Reported by Michael Balter; with commentary from Azeen Ghorayshi who broke the first of the recent spate of stories.

Human evolution is more a muddy delta than a branching tree. By John Hawks

Scientists finally detected gravitational waves. Nicola Twilley has a beautiful story about how it happened and what it means. Nadia Drake has a shorter but equally good explainer, and also talks about the rumour-mongering that preceded the announcement. Allan Adams writes about the sound of gravitational waves. And  Rachel Feltman has the most delightful story coming out of the discovery: “This is actually the second time she’s broken an embargo with a cake.”



Some troubling data oddities in a money priming study

Does it take too long to publish research? (Spoiler: yes)

A rare albino turtle hatches

“Space is hard. Engines are hard.” “Zero gravity fun time is over now.”

“We want to… guide lampreys’ movements by manipulating the landscape of fear and opportunity.”

No, an Indian man wasn’t killed by a meteorite. Sit in the corner, media sites, and think about what you’ve done

This week’s Flash Forward: what would it take to get sex robots?

New study suggests sleep deprivation markedly increases false confessions

What will it take to get plastics out of the ocean?

How the Fight Over Transgender Kids Got a Leading Sex Researcher Fired

Scientists make artificial tissue with commercial cotton candy machine

Johns Hopkins to Perform First HIV-Positive Organ Transplants in US (to HIV-positive patients, obviously)

Fighting cancer with cancer

This parasite hasn’t had sex in 10,000 years and it still probably gets more action than you.

Scientists will sequence the genome of every kakapo to find the gene for shagging Mark Carwardine’s head.

Hidden Epidemic of Fatal Infections Linked to Heart Surgeries

How would you actually prove that Zika causes birth defects?

I freeze first. Then try to escape. Only later do I consider avoid, fight, retaliate.”

DarkFly! Flies reared in the dark for 60 years give up their genetic secrets

A Skeptic Infiltrates a Cruise for Conspiracy Theorists

150,000 penguins die after giant iceberg renders colony landlocked

On video games and aggression.



Where are the women in science journalism? The Science Byline Counting Project

Palaeontologists, I have big news for you

A site that offers free access to academic papers moves to the dark web

Yep, all the time

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Are These Crime Drama Clues Fact or Fiction?

Steven Avery, featured in the Netflix documentary Making a Murderer, served 18 years in prison for rape, then was exonerated by DNA. He was convicted of murder in 2007, based partly on DNA evidence.
Steven Avery, featured in the Netflix documentary Making a Murderer, served 18 years in prison for rape before being exonerated by DNA in 2003. In 2007, he was convicted of murder, based partly on DNA evidence.

I’m often just as surprised by what forensic scientists can’t do as by what they can. In the Netflix documentary Making a Murderer, for instance, the question of whether police planted the main character’s blood at a crime scene comes down to whether or not the FBI can detect a common laboratory chemical called EDTA in a bloodstain.

On a TV crime show, this would be a snap. The test would take about five minutes and would involve inserting a swab into a magic detector box that beeps and spits out an analysis of every substance known to humankind.

In real life, there’s no common and accepted test in forensic labs for EDTA even today, nine years after the FBI tested blood for the Steven Avery trial featured in Making a Murderer. In that case, the FBI resurrected a test they had last used in the 1995 O.J. Simpson trial, and testified that the blood in question did not contain EDTA and therefore was not planted using EDTA-preserved blood from an evidence vial. (Avery was convicted.)

Questions about the test’s power and reliability have dogged the case ever since. There’s even an in-depth Reddit thread where fans of the Netflix show are trying to sort out the science.

Having worked in chemistry labs, it surprised me at first that this analysis would be difficult or controversial. After all, a quick search of the scientific literature turns up methods for detecting low levels of EDTA in everything from natural waters to beverages.

Steven Averys
Steven Avery’s attorneys Jerome Buting (shown) and Dean Strang struggled to dispute chemical evidence introduced mid-trial that undermined the idea that police had planted blood evidence.

But the key here is that we’re talking about forensic science, not beverage chemistry. Beverage chemistry, in this case, is much more exacting. Was there really no EDTA in the blood swabbed from victim Teresa Halbach’s vehicle, or was the chemical simply too diluted or degraded to be detected with the FBI’s method? Could the test have missed a small amount of EDTA? It would be hard to say without further experiments that replicate crime scene conditions, experiments that essentially put the test to the test.

The reality is that forensic science today is a strange mix of the high-tech and the outdated, so questions about evidence like those in Avery’s case are not uncommon. Methods that we take for granted, like measuring a particular chemical, or lifting a fingerprint off a gun and matching it to a suspect, can be difficult—and far from foolproof. On the other hand, some of the real science happening now sounds like something dreamed up by Hollywood script writers, such as new methods aiming to reconstruct what a person’s face looks like using only their DNA.

Making a Murderer, whether it sways your opinion on Steven Avery or not, has done a service by getting people interested in something as arcane as EDTA tests, and by showing why real-life crimes are not solved nearly so neatly as fictional ones.

I see the messiness of forensic science all the time, because I scan its journals and often come across new studies that make me think either “you mean we couldn’t already do that?” or “I had no idea that was possible.” I’ve gathered a few recent examples for a quiz.

How well can you separate CSI fact from fiction? Here are a few crime-solving scenarios I’ve cooked up; see if you can tell which use real methods based on new forensic research. You’ll find the answers below.

  1. A skeleton is found buried in a shallow grave. The body’s soft tissues have completely decomposed, so only the teeth and bones remain. A forensic anthropologist examines the bones and reports that they come from a female who was five foot six inches tall, and obese. Could she really tell the person was overweight?
  2. The body of a white male in his 50s turns up on a nature trail, scavenged by animals. The victim’s bones show a number of puncture wounds consistent with animal bites, but x-rays reveal fine lines of different density in the bone around some of the punctures. An expert says these lines show that the wounds were made about 10 years before death. Is it possible to tell the approximate age of these wounds from x-rays?
  3. A woman is found dead in her home, bludgeoned to death. A bloody frying pan lies on the floor next to her. Her husband is the main suspect. Fingerprints on the pan’s handle are too smudged to make a definitive ID, but an analyst says she can still rule out the husband: All of the fingerprints on the pan came from a woman, the expert says. Is it possible to tell if the fingerprints were from a male or female?
  4. A woman is sexually assaulted and identifies her male attacker in a lineup. The suspect’s DNA matches DNA found on her body. It looks like an easy case for the prosecutor—until the suspect reveals that he has an identical twin. Neither twin admits to the crime. Is it possible to tell which twin’s DNA was found at the crime scene?
  5. A witness sees a man in a stocking mask rob and shoot a man outside his home. A stocking is found near the house, and a hair-analysis expert testifies that 13 hairs in the mask are all human head hairs from an African-American. A microscopic analysis matches the characteristics of one hair to a particular African-American suspect. The prosecutor tells the jury that the chances are one in ten million that this could be someone else’s hair. Can hairs be matched to an individual this accurately?


Answers Below


  1. Yes. Biologists have long known that greater body mass changes the weight-bearing bones of the legs and spine, and a new study shows that even bones that aren’t supporting most of the body’s weight, such as arm bones, have greater bone mass and are stronger in obese people. So even in a skeleton missing its legs, our forensic anthropologist might be able to tell that the person was obese.
  2. No. This one is from an actual episode of Bones (The Secret in the Siege, Season 8, Episode 24, reviewed here by real-life bioarchaeologist Kristina Killgrove). In the episode, Dr. Temperance Brennan uses Harris lines to determine the age of bone injuries in two victims. Harris lines are real, but they form only in growing bones, so are useful only in determining childhood injuries or illness.
  3. Yes. A study published in November showed that the level of amino acids in sweat is about twice as high in women’s fingerprints as in men’s. Of course, as with all the new methods, this one could face challenges as evidence in a U.S. court of law, where the Daubert standard allows judges to decide whether scientific evidence is admissible based on factors including its degree of acceptance by the scientific community.
  4. Yes, if you do it right. Standard DNA tests don’t distinguish between twins, who are born with nearly identical DNA, but it’s possible to do a more sophisticated test to catch post-birth mutations and epigenetic differences, which you can think of as genetic “add-ons” that don’t affect the DNA sequence itself. One new test distinguishes between twins by looking for small differences in the melting temperature of their DNA that are caused by such epigenetic modifications.
  5. No. The field of hair analysis has come under heavy scrutiny, especially after a review by the U.S. Justice Department revealed major flaws in 257 out of 268 hair analyses from the FBI. The case described here is the real-life case of Santae Tribble, convicted in 1978 of murder. In 2012, DNA tests showed that none of the hairs matched Tribble—and one was from a dog.

Laelaps is On the Move

On the Watchman Trail at Zion National Park, Utah. Photo by Tracey Switek.

I can’t remember the exact date anymore, but sometime last month I reached my six year science blogiversary.

I was just a directionless Rutgers University undergraduate at the time I started writing. I loved paleontology, but was unsatisfied with my college education, so I pursued the subject on my own time and used my blog to enthuse about what I was learning. I had no idea that I’d end up writing for the likes of Wired, Smithsonian, Slate, and Nature, not to mention have two books already behind me.

I’m incredibly fortunate to geek out about prehistory for a living, especially since my career is the accidental outcome of what started as a personal experiment. For the past two years, Wired Science has been my lab for part of that ongoing experiment. With all the dinosaurs penned up over at Smithsonian, this has been my place to play with horseshoe crabs, sharks, sabercats, crocodiles, flightless birds, and, of course, bear dogs (like the one that graces this blog’s banner).

But I’ve stretched myself too thin. Feeding two high-profile science blogs is extremely difficult. I feel like I’ve let Laelaps lag as I’ve tried to keep moving forward with books, articles, and other projects. I’ve been looking for a way to fold my efforts back under one header, and I was recently offered an opportunity to do so at a new home.

Today, I’m saying farewell to Wired Science, and soon I’ll be leaving Dinosaur Tracking, as well. I can’t say where I’m going, not just yet, but Laelaps will return and bring dinosaurs back into the flow of the blog. Don’t think of this as a goodbye – it’s more of a “This animal is temporarily off exhibit” sign.

Before I go, though, I must say that I’m deeply indebted to editor Betsy Mason for jumping at the chance to bring Laelaps to Wired Science. I’ve been proud to blog alongside fantastic and incredibly kind writers such as Deborah Blum, David Dobbs, Maryn McKenna, and Sam Arbesman.

For now, I’m going to take a deep breath, have a strong drink, and then get back to work on new material for the next iteration of Laelaps. I’ll announce the news on Twitter and Facebook in due time, and, when everything is unveiled, I hope that you all follow me over to my new home.

Carnivorous Neighbors — How Sabercats and a Bear Dog Managed to Coexist

A restoration of the large bear dog Amphicyon at a kill. Spain’s Magericyon anceps was a relative of this imposing carnivore. Art by Charlene Letenneur, from Argot, 2010

Prehistoric predator traps are wonderful things. From the Allosaurus-dominated bonebed at the Jurassic Cleveland-Lloyd quarry in eastern Utah to the dire wolf and Smilodon-filled graveyard of Los Angeles, California’s La Brea asphalt seeps, predator-rich fossil deposits provide paleontologists with a wealth of information about animals that were relatively rare in the habitats they stalked. After all, an ecosystem can only carry so many large carnivores. Any site containing multiple individuals of an apex predator is a bonanza for researchers.

Another such site, the focus of a new Proceedings of the Royal Society B study by University of Michigan paleontologist Soledad Domingo and colleagues, is entombed within the 10- to 9-million-year-old rock at Cerro de los Batallones in Spain’s Madrid Basin. Paleontologists working this locality have found at least nine different assemblages of large fossil mammals, and two of these deposits are exceptionally rich troves of carnivore bones.

Out of 1,800 large mammal fossils recovered at one of these sites, about 92 percent belong to 10 different species of carnivorans of various size. There are the remains of small cats, skunks, a civet-sized hyena, and a red panda relative, but the bonebed is especially abundant with the vestiges of three apex predators that lived alongside one another. In addition to a pair of sabercats – the leopard-sized Promegantereon ogygia and the tiger-scale Machairodus aphanistus – there lay the bones of the large, heavily muscled bear dog Magericyon anceps.

None of these large Miocene carnivores have living descendants, or even modern analogs. We can only approach the hunting habits of these species through the fossil record and the limits of scientific imagination. This leaves us with a mystery – how did these three ancient carnivorans manage to coexist? To investigate that question, Domingo and co-authors drew upon geochemical clues they drilled out from the teeth of the carnivores and their potential prey.


Scientists Reveal Jurassic Forest’s Hidden Hangingfly

A fossil of the Jurassic hangingfly Juracimbrophlebia ginkgofolia (C) next to the leaf of the ginkgo Yimaia capituliformis (E) found in the same deposits. From Wang et al., 2012.

At first glance, the newly-named fossil hangingfly Juracimbrophlebia ginkgofolia doesn’t look especially impressive. Found in the roughly 165 million year old beds of China’s Jiulongshan Formation, and described by paleontologist Yongjie Wang and colleagues today in PNAS, the insect looks quite similar to its thin-bodied, stilt-legged, long-winged living relatives. But when taken in context with the various other organisms found in the same beds, a subtle connection comes into focus. The ancient hangingfly, Wang and co-authors propose, was a mimic of Jurassic ginkgo trees.

Mimicry isn’t a new development among insects. The evolutionary connection between arthropods and the vegetation they resemble may go back over 300 million years, and, among modern forms, has adapted insects so intricately that they even show markings similar to fungus and lichen common on the plants they are supposed to look like. Juracimbrophlebia isn’t even the first mimic insect to be found in the high-resolution fossil slabs of the Jiulongshan Formation. Nevertheless, this is the first time a hangingfly has been found to mimic a plant.

A restoration of Juracimbrophlebia ginkgofolia hiding among Jurassic ginkgo leaves. Art by Wang Chen, from Wang et al., 2012.

In order to blend in on the Jurassic ginkgo Yimaia capituliformis, tricky Juracimbrophlebia had to spread its wings. When held just so, the elongated, veined wings of the insect resembled the multi-lobed shape of the ginkgo leaves. This is assuming that the mimicry hypothesis is correct. The insect and the leaves show a close resemblance, but how can we test this hypothesis 165 million years after these organisms shared the same forest? The hangingfly does resemble the ginkgo, that much is clear, but how can we tell whether or not the insect’s anatomy was a form of camouflage or just coincidentally similar?

But let’s run with the mimicry hypothesis. Under this scenario, Wang and collaborators propose that the hangingfly might have been hiding from the insectivorous mammals, dinosaurs, pterosaurs, lizards, and amphibians that inhabited the same forest. (The same cast of arthropod-crunchers was recently cast as a threat to the katydid Archaboilus musicus, found in the same formation and known from a set of wings researchers recently used to reconstruct the insect’s song.) Alternatively, Juracimbrophlebia might have been a predator itself – the hangingfly could have ambushed the various insects which fed upon prehistoric ginkgo trees. Perhaps the mimicry proved advantageous in both respects. The span of time between us the Jurassic forest prevents us from knowing – such tantalizing traces of prehistoric interactions only come to life in our imaginations.


Wang, W., Labandeira, C., Shih, C., Ding, Q., Wang, C., Zhao, Y., Ren, D. 2012. Jurassic mimicry between a hangingfly and a ginkgo from China. PNAS www.pnas.org/cgi/doi/10.1073/pnas.1205517109

A Feast of Feathery Fossil Posts

The reconstructed skeleton of Diatryma. Photo by Flickr user Ryan Somma.

Tomorrow is Thanksgiving, and the American holiday wouldn’t be the same without moist slabs of gravy-drenched dinosaur meat on the table. Of course, our species was not the first to dine on dinosaur, not by a long shot, but we do it with a bit more style than the alligators, lice, sharks, and other creatures I mention over in my new Slate article on Mesozoic dinosaur feasts.

Given the nature of the celebration, it’s only fitting that I present some leftovers, too – some of my favorite posts about prehistoric birds. Imagine what the giant Eocene bird Diatryma, or South America’s fearsome terror birds, could contribute to the turducken trend. The fossil record has also introduced us to huge, colorful penguins and pumped-up storks that probably squabbled with island-dwelling hominins over dwarf elephant carcasses, though neither of them was quite so strange as the banana-winged Xenicibis. Not every prehistoric bird is known from bones, thoughfeathers and eggshells can tell us about ancient birdlife, as well. (And I should mention that if you happen to be in the mood for fresher fare, this new paper about how feathery dinosaur arms evolved to become true wings is worth a read.) Indeed, birds have been carrying on the dinosaur legacy ever since the end-Cretaceous cataclysm wiped out their relatives 66 million years ago, and their relationship to Velociraptor and kin can be clearly seen in the anatomy of your holiday bird.


Great White Shark Ancestry Swims Into Focus

A restoration of Carcharocles megalodon at the San Diego Natural History Museum. Although such restorations are based on teeth and the anatomy of modern great white sharks, new evidence indicates that the two sharks were only distant cousins separated by millions of years of evolution. Photo: Brian Switek / Wired

Few predators terrorize our imaginations as fiercely as the great white shark. The immense fish is sublimely attuned to an environment that is alien to us, and, despite the rarity of accidents, the nightmare of slipping down the shark’s throat has obscured the fact that we have done far worse things to these apex predators. And, in a culture where bigger is frequently confused with better, the great white’s prehistoric cousin Carcharocles megalodon has gained almost as much fame. A 15-foot-long white shark is imposing enough, but the 50-foot-long version has inspired even more awful novels and blood-soaked b-movies than its living relative.

Today’s Carcharodon carcharias and the extinct Carcharocles megalodon have often been linked together on account of their teeth. With the exception of rare vertebrae, that’s really all we know of the “megashark.” The rest of the shark’s cartilaginous frame has never been found, and may forever remain that way. Still, since the triangular, finely serrated teeth of Carcharocles megalodon roughly resembled the more coarsely serrated teeth of today’s great white sharks, some ichthyologists and paleontologists connected the two together as close relatives – if not actually ancestor and descendant. The great white shark could be a dwarfed version of its massive, whale-crunching forerunner, or a very close cousin.

Not everyone has agreed that the two sharks were close kin, though. In fact, recent analyses have underscored a different scenario that drives a wider gap between the two sharks.

The teeth of modern great white sharks are broadly similar to those of Carcharocles megalodon, but they differ in the specifics. In detail, great white teeth more closely resemble those of broad-toothed mako sharks, of the sort seen in the fossil species Carcharodon  (formerly “Cosmopolitodus“) hastalis. Today’s great white sharks are more likely modified broad-tooth makos, with Carcharocles megalodon falling within a separate subgroup in the same shark family (called Lamniformes) that branched from the great white lineage sometime during the Cretaceous.

A paper just published by Monmouth University paleontologist Dana Ehret and colleagues in Palaeontology supports the growing consensus behind the broad-tooth mako link, and does so through the description of a new shark species. Discovered in 1988 within southwestern Peru’s Pisco Formation, the previously unrecognized shark species is represented by an absolutely gorgeous specimen – a beautifully preserved set of fossilized jaws, with teeth still in their original positions, and a short string of articulated vertebrae. Following a previous 2009 study of the fossil, Ehret and colleagues have now named the shark Carcharodon hubbelli in honor of fossil shark expert Gordon Hubbell. The species appears to be an intermediate form between today’s great white sharks and their broad-tooth mako ancestors.


Eocene Big Bird Not so Scary, After All

A pair of footprints left by a giant, 53 million year old bird. Could these be traces of Diatryma? From Mustoe et al., 2012.

The reign of the dinosaurs came to a catastrophic end 66 million years ago. That’s the common trope, anyway – a holdover from before we recognized that at least one feathery lineage survived and proliferated after the K/Pg devastation. We still live in the Age of Dinosaurs – a 230 million year old success story carried on by modern birds.

Still, even today’s birds seem to pale in comparison to their long-lost relatives. In the Eocene world that emerged from the vestiges of the Late Cretaceous, giant avian dinosaurs left their mark on the landscape. I mean that literally. In the latest issue of Palaeontology, Western Washington University paleontologist George Mustoe and co-authors present a set of several 53 million year old tracks made by an enormous bird that once strode across North America.


Pterosaur Takeoff Tussle Highlights Science News Fumble

Earlier this week I received a press release about pterosaur takeoffs from Texas Tech University. Rather than launching into the air through a pole-vault motion, as paleontologists such as Michael Habib and Mark Witton have argued (check out the video), the email said that giant pterosaurs such as Quetzalcoatlus required a “10-degree downhill slope” where they could “taxi” by running and flapping before taking off. Only under such restricted conditions could an animal with a 34 foot wingspan get into the air, the release claimed.

I didn’t pay much attention to the news suggestion. There were no details about the actual science, presented at the annual Geological Society of America meeting in Charlotte, North Carolina, and the study came from controversial paleontologist Sankar Chatterjee and colleagues. Previously, Chatterjee confused a crocodile cousin for a tyrannosaur ancestor, wrongly touted an assemblage of isolated bones from different animals as the first bird, and, despite the lack of evidence, proposed that some crested pterosaurs windsurfed through Mesozoic waters.

Every scientist makes mistakes, and being wrong some of the time doesn’t mean a researcher is perpetually in error, but, in this case, I didn’t trust the source and the hypothesis made no sense to me. How could large-bodied pterosaurs have possibly survived if they always required just the right slope and just the right wind direction to take off? When there’s a tyrannosaur or Deinosuchus nearby, you really don’t want to wait to get into the air. I felt Habib’s quad-launch idea was better-supported, and, since the press release was based on a talk without any paper to look at, I figured I’d wait for a publication to write about the topic.

But other news sources decided to pick up the story. A basic rundown of Chatterjee’s proposal popped up at LiveScience, syndicated over at the Huffington Post, and on other web-based news sites. None of them mentioned previous work by Habib and Witton. Even LiveScience, which ran a story about Habib’s paper on the subject in 2009, neglected to get an outside comment or even acknowledge other perspectives on the topic.

Witton rightly excoriates the press coverage of Chatterjee’s press release over at the Pterosaur.net blog:

By bigging up their abstract rather than a peer-reviewed publication in which their methodological details and discussion are explained in detail, Chatterjee et al. have given the impression that their work is more scientifically credible than it actually is. Science journalists have lapped the release up, presumably because giant pterosaurs are cool, but they have not mentioned the lack of a detailed peer-reviewed study behind the findings, nor (in the majority of cases) bothered to find out what other palaeontologists make of the story.

As Witton notes in the same post, this isn’t the first time press releases have been parroted through online news sources – last year’s GSA meeting, for example, gave birth to the fantastic “artistic Kraken.” The trend isn’t new, and highlights a never-ending problem in the online science communication ecosystem.


Smilodon the Vampire

A cast of Smilodon at the Natural History Museum of Utah. Photo by the author.

Aside from the woolly mammoth, no Pleistocene creature is more iconic than Smilodon. The vanished sabercat is a symbol of North America’s recently lost megafauna, but it’s also an Ice Age mystery. While the carnivore broadly resembled other felids – a cat is a cat is a cat – the predator’s fangs have confounded paleontologists for over a century. The sabercat’s impressive canines have been envisioned as slicing and stabbing weapons in multiple attack scenarios, including an offhand comment that cast Smilodon as a vampire.

Even though the literature of Smilodon and its awful gape grows with every passing year, John Merriam and Chester Stock’s 1932 monograph The Felidae of Rancho La Brea remains the essential reference on the famous asphalt seep’s cat fossils, most of all Smilodon. When Merriam and Stock compiled the book, though, no one knew how Smilodon hunted. Such enormous canines were obviously killing weapons, but how were they employed?

The La Brea researchers saw the canines of Smilodon as serrated knives. “In consummating an attack,” Merriam and Stock wrote, “the head would be drawn back by the powerful muscles lodged in the neck and attached to the occiput, while the lower jaw moving through a wide arc permitted the sabre-like canine teeth to function as stabbing weapons.” How Smilodon got in position to repeatedly slam its mouth into a bison or mastodon’s hide, the paleontologists didn’t say.

But there was another subtle feature that Merriam and Stock mentioned in passing that caught my attention when I read their monograph. Envisioning “the concluding moments of the attack,” the scientists pointed out that Smilodon had a “heavily corrugated gum which presumably covered the hard palate,” and that this feature “may have been advantageous in blood sucking.” Imagine a Smilodon crouched over a freshly killed horse, fangs buried to the hilt, slurping blood from the wounds.

There’s no evidence that Smilodon or any other sabercat was a specialized blood-sucker, though. The idea was a throw-away comment in a brief and speculative account of how the beast might have fed. Multiple analyses since the time of Merriam and Stock have rejected the stabbing hypothesis, and affirmed that Smilodon probably killed horses, camels, bison, baby mammoths, and other mid-sized herbivores of its time with bites to the neck or belly. Much like visions of leaping, carnivorous mastodons, blood-sucking sabercats have only ever existed in our imaginations.


Andersson, K., Norman, D., Werdelin, L. 2011. Sabretoothed Carnivores and the Killing of Large Prey. PLoS ONE 6, 10: e24971. doi:10.1371/journal.pone.0024971

Merriam, J., Stock, C. 1932. The Felidae of Rancho La Brea. Carnegie Institute of Washington Publications, 442: 1-231

Turner, A., Antón, M., Salesa, M., Morales, J. 2011. Changing ideas about the evolution and functional morphology of Machairodontine felids. Estudios Geológicos 67, 2: 255-276

The Fall of the Carnivorous Mastodon

A restoration of the American mastodon (Mammut americanum), previously known as the “American Incognitum.” Art by Dantheman9758, image from Wikipedia.

Extinction sucks. Only yesterday, in geologic terms, did mastodons, sabercats, giant ground sloths, and their charismatic Ice Age contemporaries roam North America. Humans even encountered these beasts, but I was born about 10,000 years too late to see the Pleistocene menagerie. I just missed some of the most wonderful mammals ever to tread the continent.

When 18th-century scientists began to scrutinize the bones of these Pleistocene megamammals, though, extinction had not yet been universally recognized as a reality. By the hand of God or the balance of nature, every creature was believed to have a perpetual role to play on the Earth’s stage. Remove even one species from that order, and the whole theater might crumble with it. No surprise, then, that naturalists such as Louis Daubenton and Thomas Jefferson thought that the weird bones coming out of Pleistocene deposits, such as Big Bone Lick in what is now northern Kentucky, represented as-yet-unknown animals that were still living in the American interior. Among these mysterious animals, naturalists believed, was a carnivorous mastodon.


Researchers Chew Over a Prehistoric Bear’s Diet

Paleontologists have been debating the diet of deep-skulled bears – such as Arctodus pictured here – for decades. Were bears such as Arctodus and Agriotherium predators, scavengers, herbivores, or some combination of the three? Art by Oscar San-Isidro, from Figueirido et al., 2010.

Of all the bears to come and go during the group’s 23 million year old history, none had a bite more powerful than Agriotherium africanum – a ursid as large as today’s grizzly and polar bears that roamed Africa during the latest Miocene and earliest Pliocene epochs. In a new Journal of Zoology paper by C.C. Oldfield, Colin McHenry, and colleagues, virtual models used to run bite tests predicted that the fossil bear could bring its canines down with 4566 Newtons of force – the equivalent of about one thousand pounds of pressure. The question is why this huge extinct bear required such a powerful bite.

For some prehistoric creatures, it isn’t difficult to envision their feeding habits. Tyrannosaurus rex undoubtedly clamped its heavily-fanged jaws on struggling Edmontosaurus and rotting Triceratops, and so the dinosaur’s overwhelming bite strength makes sense given its hypercarnivorous lifestyle. But the connection between skull anatomy, bite force, and diet isn’t always so clear.


Variety is the Spice of Life

A restoration of of Triassic weirdo Vancleavea. Art by Smokeybjb, from Wikipedia.

This past week, I attended the 72nd Society of Vertebrate Paleontology meeting in Raleigh, North Carolina. I’m still on the mend from the science hangover. Still, while my memories are relatively fresh, I want to mention one of the important themes that ran through some of the meeting’s sessions.

Paleontologists are drawing more information from prehistoric bones than ever before. A fossil femur or petrified pelvis isn’t just an anatomical object, but a time capsule entirely composed of more subtle clues about ancient life. Among other lines of evidence, a bone’s microstructure – or histology – preserves clues about an individual animal’s growth and physiology. In the ongoing discussion about dinosaur biology, for example, histology has helped paleontologists better understand how quickly Triceratops and company grew up, and how radically the fossil celebrities changed as they aged.

As informative as histology can be, though, the conclusions we draw from bone must be tempered by how much remains unknown. As paleontologist Sarah Werning aptly pointed out in her presentation on marsupial histology, what we know about mammal growth is constrained by an unbalanced dataset biased towards animals of economic important and zoo animals. Some groups, such as marsupials, have been almost entirely ignored, and this inhibits our ability to understand basic aspects of mammal biology.

How, then, can we accurately interpret prehistoric evidence when we don’t fully understand living species? Consider a study on mammal bone published this year regarding regular slowdowns in growth, recorded in parts of the skeleton as rings called “lines of arrested growth” (LAGs). These features were previously thought to be a characteristic of ectothermic animals – crocodiles, lizards, and the like – whose body temperatures are regulated by the surrounding environment. Since dinosaur bones show LAGs, too, some researchers made the case that the great saurischian and ornithischian tribes were either ectothermic or had some kind of metabolism halfway between the “typical” mammal and reptile. Yet, as the new study showed, even endothermic mammals lay down LAGs in response to cold or dry seasons, and this therefore obliterates the tie between LAGs and a set physiological profile. If the present is truly the key to the past, we need to do a much better job of sampling modern animals.


Paleontologists Reveal the Identity of ‘Predator X’

“Predator X” chomps on one of its long-necked plesiosaur neighbors. Despite such restorations, though, we know very little about what the big pliosaur truly looked like. Image credit: Atlantic Productions.

Paleontology often relies on superlatives to entice the public. Fossil species are touted as being the biggest, oldest, strongest, weirdest, or whatever other –est applies if the designation will help popularize a discovery. But, sometimes, hype precedes science.

In 2009, journalists heralded the arrival of “Predator X” – an immense, big-headed marine reptile said to have a bite four times stronger than Tyrannosaurus rex (the perpetual yardstick for all things prehistoric). The leviathan had only recently come out of the ground, and the researchers who discovered the aquatic hunter had not yet published a technical description of the beast, but news reports, a History Channel documentary, and even an unrelated schlock film declared the little-known pliosaur as the most badass predator of all time.

Six years after the fossil’s initial discovery, and three years after the peak of all the sensationalism, Predator X finally has a formal name. In the Norwegian Journal of Geology, paleontologists Espen Knutsen, Patrick Druckenmiller, and Jørn Hurum have dubbed the creature Pliosaurus funkei. (You’ll remember Hurum as the scientist star of the Predator X documentary, as well as the ringmaster who organized the media circus for “The Link” shortly thereafter.) But does the Jurassic ichthyosaur-cruncher live up to the media bombast?


The Family That Nests Together, Rests Together

A Cape Gannet breeding colony at Bird Island Nature Reserve near Lamberts Bay, Western Cape, South Africa. Photo by Octagon, image from Wikipedia.

Fossils tell stories. I’ve written about this beautiful fact over and over again, but the multiple perspectives on prehistoric life afforded by even the most mundane petrified scrap never cease to impress me. Fossils are not merely individual facts of nature that educate us simply by their identification and accumulation. They are more than that – primeval touchstones that can send us down any number of pathways as we trace evolutionary history. Such ancient inspirations can be as simple as a fragment of turtle shell or a shed trilobite exoskeleton, and, as recently shown by paleontologist Gareth Dyke and colleagues, as grand as the remnants as a drowned bird colony.