Laelaps

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Dr. Jack Horner is one of the most recognized paleontologists working in the field today, and is presently the Ameya Preserve Curator of Paleontology and Montana State University Regents’ Professor of Paleontology. He has authored numerous books, papers, and popular articles, and during his career has named the dinosaurs Maiasaura peeblesorum, Orodromeus makelai, Hypacrosaurus stebingeri, Prosaurolophus blackfeetensis, Gryposaurus latidens, and Brachylophosaurus goodwini, although he is probably most well-known for his studies of the eggs & young of Maiasaura. This week I had the chance to ask Dr. Horner about his work and thoughts about dinosaurs;

[Brian Switek] What first inspired you to become a paleontologist, and what keeps you going back into the field year after year?

[Dr. Jack Horner] Near as I can remember, I was born wanting to be a dinosaur paleontologist. This will be my 40th consecutive year in the field. Every specimen I find generates the same amount of excitement as I experienced the first time I found a dinosaur, and regardless of how many I find representing a single species (ie: Triceratops or Maiasaura), I still feel the same excitement. Every new specimen offers something new.

[Switek] In your book Dinosaur Lives you wrote “A dinosaur out of context is like a character without a story. Worse than that, the character suffers from amnesia.” In terms of ecological context, what was the Upper Cretaceous of Montana like during the time that dinosaurs such as Maiasaura lived?

[Horner] First off, that quote is in reference to specimens taken from the field before the proper scientific studies have been completed.

As for the ecology of Maiasaura, there are clearly different scenarios for the different ages of individuals. Maiasaura hatched out of their eggs in the confines of bowl-shaped mud nests, and remained in these nest-like structures until they had more than doubled their hatchling size. The nests we’ve found were on the over-banks of small streams, and these streams flowed into shallow lakes. The streams and lakes were surrounded by various conifers, and low-growing bushes. Volcanoes existed some 50 miles to the south of the nesting ground, and the Cretaceous Intercontinental Seaway was approximately 300 miles to the east. the newly forming Rockies were about 20 miles to the west. Tropical storms, possibly even hurricanes tracked northward from the Gulf of Mexico, causing devastation along the coastal plain. An aggregation of several thousand Maiasaura adults and juveniles were killed in either a storm such as this, or possibly a catastrophic eruption of the nearby volcano. A bonebed of Maiasaura containing thousands of their bones attests to this event.

[Switek] In 1978 you discovered a number of skeletons of baby Maiasaura, sparking a major change in what was known about dinosaur reproduction. What was early life like for a baby Maiasaura, and how might it have differed from the early lives of some of the theropods like Troodon that lived nearby?

[Horner] Unfortunately taphonomic information doesn’t provide this kind of data. Maiasaura nested along rivers, and Troodon nests are found on what is interpreted as islands and the shore of the lakes. Maiasaura and Troodon both died in the catastrophic event.

[Switek] In many documentaries and in your book The Complete T. rex you suggest that Tyrannosaurus was more of a scavenger than a hunter. Bob Bakker and other paleontologists advocate that Tyrannosaurus was an active predator. Do you think that our understanding of the paleobiology of the massive theropod has benefited from this debate, and what are your current thoughts about the habits of the famous dinosaur?

[Horner] Scientific inquiry is about method rather than conclusions. When we “do” science we create hypotheses based on physical evidence, and then attempt to falsify these hypotheses by discovering contrary evidence. Science is about falsification, not verification. As an educator, my primary job is to show people, including kids, how science works, so that they too can then search for contrary evidence. I also teach kids that if they are only interested in being right, then science is the wrong field to go into. If they are interested in finding the right answer, then it is likely that they will be often wrong. I also teach people that most preconceived ideas are wrong, because they are seldom based on physical evidence.

So, as there was never any physical evidence provided to support an actual hypothesis that T-rex was an active predator, we should, as good scientists begin our search without any preconceived ideas. In other words we should begin by asking how did T-rex acquire its meat?

What I did was to make a comparison of a T-rex skeleton with that of a Velociraptor, since we have pretty good evidence (from the fighting dinosaurs of Mongolia) that Velociraptor was a predatory dinosaur. We don’t however, have any direct evidence such as this for any other meat-eater. And, we should not assume that all meat-eaters were necessarily predators, because scavenging is certainly an option.

Comparing T-rex with Velociraptor, virtually all characters are the opposite of one another. T has short arms, V has long arms, T has long femur/short tibia, V has short femur/long tibia, T has large olfactory, V has small olfactory, T has bone-crushing teeth (and gains them during ontogeny), and V has bladed-shaped meat-slicing teeth, T is common in its ecosystem, and V is rare.

The opposite characters suggest that T-rex is doing something very different from Velociraptor, and its bone crushing teeth suggest it was likely a scavenger. Suggesting that it was both would not be falsifiable, but hypothesizing that it is 100% scavenger can likely be falsified if incorrect. Personally, I don’t care how T-rex got its meat, but I do care that kids understand how we do science. I also care that they realize that opinions are not scientific even if they are the opinions of scientists. Physical evidence is the most important ingredient in science. Parsimony is the second most important! The simplest (least number of steps) explanation based on the physical evidence? The third most important is phylogeny. Dinosaurs are related to extant birds and crocodilians, and so our initial explanations should be based on related taxa. Some birds are exclusive scavengers, so its not complicated to suggest that T-rex was an exclusive scavenger.

[Switek] At the last SVP meeting in Texas, you, Holly Woodward, and Mark Goodwin proposed that the pachycephalosaurs Stygimoloch and Dracorex were really juvenile representatives of Pachycephalosaurus (an idea that Bob Bakker has also recently challenged). Can you elaborate on the similarities that led you to this hypothesis?

[Horner] I’ve known Bob for many years, and like him a lot. He’s a very bright guy, but in this case especially, he’s just not thinking ontogenetically. Dinosaurs change as they grow up, and some of them change drastically. Crested duck-billed dinosaurs are a clear case of this, as is the extant dinosaur Cassowary. Cassowary doesn’t acquire its crest until the skull of the bird is 80% adult size. That means that a juvenile and adult look very different from one another, and can be almost identical in size.

Dracorex, Stygimoloch and Pachycephalosaurus specimens vary in size from Dracorex being the smallest, Stygimoloch second, and Pachycephalosaurus, the largest. On top of that the cranial ornamentations of these three taxa are identical except for the size of the sqaumosal spikes and the dome. Bob states in his interview that Triceratops didn’t have any “reversals” where the bone grew to a particular size and then reversed getting smaller, but that is not true, for as I showed in my SVP talk, Triceratops eppocipitals do in fact grow from small triangular shapes to large triangular shapes, and then reduce to flatten against the frill. You can see this shape change in a paper Mark Goodwin and I have just published in the new JVP.

We have evidence, based on histological sections of several spikes, that the spikes did in fact increase in size, and then reduce in size, with spike reduction corresponding to the enlargement of the dome. And, there is more of this cranial shape change in these animals that I cannot tell you about at this time, as the paper is soon to go to review. This is also true of Triceratops. Cranial shape change was extreme in the marginocephalian dinosaurs, and it all has to do with the extraordinary kind of bone tissue that makes up their skulls. Not at all like the tissues that make up the skulls of mammals.

As an added piece of information, on account of the extraordinary cranial bone tissues, pachycephalosaur skulls would have shattered had they butted heads. These dinosaurs most likely had vertebral locks to help hold up their heavy heads, for these animals have the heaviest, densest bone of any animal we have on record.

[Switek] In addition to writing several books and appearing in countless documentaries, you’ve also advised the production teams for all the Jurassic Park films about dinosaurs. Is it difficult being such a well-known paleontologist, balancing your technical work with popularizing paleontology?

[Horner] Nope, its all the same thing, its all about education. I’m very happy that so many people are as interested in dinosaurs as I am.

[Switek] Many of the readers of this blog are students hoping to be professional paleontologists themselves someday. Do you have any advice for college students who want to pursue a career in paleontology?

[Horner] Strive to be a good, objective scientist, understanding that if you are indeed more interested in being right than in having the right answer, you should go into politics. Also, keep in mind that a paleontologist needs to always be thinking in terms of stratigraphy, taphonomy, phylogeny and ontogeny. And of course, about education. The most important character you can possess if you really want a paleontology career is passion. You have to be passionate about your endeavor because there is a lot of competition. Be the best, and you will get the best job!

[Switek] Paleontology is a field that is rich in history and colorful personalities. Is there any paleontologist, past or present, that has served as an inspiration for your own work?

[Horner]When I was a little kid I had the book All About Dinosaurs by Roy Chapman Andrews, and always wanted to go to Mongolia to help find the dinosaur eggs, and see the double-humped camels, and walk around the Flaming Cliffs.

Now, fifty years later, after having been there many times, we’ve built a preparation laboratory there, and I have two Mongolian graduate students, and a Mongolian Post-Doc. I feel like I have had a part in helping the Mongolians create their own paleontology research and education projects so that when future kids read books about Mongolian dinosaurs, they will want to be like the Mongolian scientists, rather than like some American or other foreigner.

Other Interviews in this series

Dr. Robert Bakker

Comments

#1 Michael D. Barton, FCD
April 11, 2008

Horner: “First off, that quote is in reference to specimens taken from the field before the proper scientific studies have been completed.”

Last semester, Horner spoke to my museum studies class at Montana State University about his paleontology field work and museum work at the Museum of the Rockies. First thing, he held up a piece of bone and asked, “Anyone know what this is?” “Vertebrae,” “dinosaur bone,” “T. rex toe bone,” – various answers. Horner replied, “It’s nothing,” and proceeded to slam the bone onto a table extremely hard, breaking into pieces. “When this bone was found, nobody recorded its location or other relevant data. It’s a worthless piece of bone, because it is out of context.” Then he proceeded to stress the importance of documentation in museum work.
#2 amanda
April 11, 2008

Another great interview! Thanks again.

I read Horner’s Digging Dinosaurs this past summer and it was wonderful…Horner is a good educator…good at putting things simply so that anyone can understand. He does a great job of cultivating enthusiasm; I was even more pumped up about studying paleontology for weeks after reading Digging Dinosaurs.
#3 Sean Craven
April 11, 2008

The whole Horner vs. Everybody Else debate regarding the feeding habits of Tyrannosaurus has been a source of fascination and frustration for years. This is the first time that Dr. Horner’s comments on the subject have made any real sense to me. I can understand the impulse behind making an extreme yet defensible argument in order to provoke reasoned thought.

But it doesn’t pan out in the real world. Every time Dr. Horner’s ideas on the subject get press I have someone I know run up to me and triumphantly declare that T-rex was a scavenger. It doesn’t make them think through the scientific process, it doesn’t make them challenge any assumptions. Instead they take the word of an authority at face value.

And not to go too deep into it. But. Until Dr. Horner can demonstrate the existence of a land-going animal that lives exclusively on carrion and then links that behavior to specific details of anatomy that exist in Tyrannosaurus than his ideas are far from parsimonious. In other words, all the evidence says that carnivores predate.

This isn’t a general slam on Dr. Horner; his work has been fascinating and valuable. I’ve read a number of his pop science books and will read more. But come on, dude, when you state in a public forum that one of the reasons you think Tyrannosaurs are scavengers because they’re ugly, like hyenas and buzzards… I mean, you can’t really bridge the gap between that nonsense and the intent to provoke scientific thought.

This was a good interview but it left me unsatisfied. I still feel as though I don’t know what Dr. Horner really means when he says this stuff. On the other hand I could just be working myself into a petulant frenzy because I dig hyenas and buzzards…
#4 Christophe Thill
April 11, 2008

Thanks !!!

Now for suggestions : among other people I would see interviewed is Zofia Kielan-Jaworowska, who doscivered the Nemegt dinosaurs. Also, during open-door days at his lab, I’ve had very pleasant talks with Christian de Muizon, discoverer of such lovely beasties as the sea-sloth Thalassocnos, and Odobenocetops, a dolphin with an asymmetrical, walrus-like head, and I think it would be great to read about him too.
#5 Mike V.
April 11, 2008

Re: Michael’s comments on Horner breaking a bone to make a point.

Perhaps Dr. Horner could have made his point without smashing a perfectly good bone? Perhaps he could have given it to an elementary school to let kids touch a real dinosaur bone. It could have inspired a child to become a paleontologist.
#6 Ed Yong
April 11, 2008

These are some great interviews Brian. Hats off to you.

And I wholeheartedly subscribe to Sean Craven’s argument about the theoretical vs. practical effects of deliberately extreme arguments.
#7 H.H.
April 11, 2008

Excellent interview. I really appreciated his desire to convey the idea that science is a method for finding truth, not for bolstering preconceived notions of correctness. We need more men like Horner to explain not just the facts of science, but why science works so darn well. “Science is about falsification, not verification. As an educator, my primary job is to show people, including kids, how science works, so that they too can then search for contrary evidence.”

This lesson needs to be conveyed way more often to the public. The search for truth is advanced by looking for contrary evidence, not merely amassing confirming evidence. I wish more people took that lesson to heart.
#8 jck
April 11, 2008

I like Horner’s definition of science, although I think if politicians thought more scientifically, this world would be much better off!
#9 Zach Miller
April 11, 2008

I’ve heard all his scavenging arguments before. Just because one animal is different, structurally, from Velociraptor doesn’t mean it didn’t hunt things! Besides that, there ARE fossil instances of T.rex apparently attacking live animals, like the Edmontosaurus with part of its tail bitten off! And then there’s that irritating fact that NOT ONE VERTEBRATE ANIMAL ALIVE TODAY (vultures included) gets its food EXCLUSIVELY through scavenging. Horsepucky. Vultures will eat carrion, sure, but they’ll also go after lizards and small mammals.

And his answer to your Jurassic Park question? HOOEY! It’s all about education? PTERANODON DIDN’T HAVE TEETH, DIDN’T FLY LIKE A BAT, AND COULDN’T CARRY PEOPLE TO ITS NESTS!

*fumes*
#10 Traumador the Tyrannosaur
April 11, 2008

Mike V-

Having fossil hunted in both the same region of Montana as Dr. Horner typical does his work, and further north in Alberta there are soooooooo many random disarticulated bones in areas that you can afford to smash some (especially those taken out of stratographic context), and still give three times as many to the local skool (though in Alberta due to the laws involved with fossil conservation it’d be easier and more LEGAL for a curator to smash a fossil than give it away to a non museum entity).

Also his point about documentation is totally founded. The Royal Tyrrell has BOXES and BOXES of useless chum bones that the public brings in. Without a location or associated material frankly hadrosaur vertabrae, rib, or digit bones are really worthless. Heck even Albertosaur teeth fall into the category of useless. They make great additions to the education departments collection of them (some 20+ of them when I left the museum), but beyond that if we don’t know where their coming from they teach us NOTHING. We can’t even safely say their Albertosaur in fact!
#11 BlueMako
April 11, 2008

I never did understand why Horner’s so damned dead-set on “T-rex was only a scavenger”, since virtually all living carnivores will both hunt and scavenge. There’s no reason to think that any less true in the past…
#12 johannes
April 12, 2008

> Some birds are exclusive scavengers, so its not complicated to
> suggest that T-rex was an exclusive scavenger.

But those birds SOAR (and, of course, some other birds are exclusive predators, or herbivores, or insectivores). There is not a single example of a terrestrial scavenger that prefers starving to hunting. People who are better at math than me have proven that it is impossible for a terrestrial, non flying animal (and in fact even for flyers that can’t soar), leave alone an active, cursorial one, to subside on carrion alone, so I think the exclusive scavenger hypothesis IS already falsified.
Excellent interview, though.
#13 Sean Craven
April 12, 2008

Since nobody else has brought it up I may as well chime in again.

One of the most troublesome aspects of the whole predator/scavenger thaaang is that it clearly demonstrates one of the major deficiencies in current US journalism.

One scientist makes an insupportable statement; his peers call him on it. This is reported in the news as a controversy rather than being either ignored or accurately described.

Not to go into a rant about dualistic thought in Western culture, but the news industry loves it when they can frame a story with two opposing opinions, smile, and say, “Well, here’s the evidence. It’s up to you to make up your own mind.”

There are times when this is appropriate but for obviously unbalanced situations like this or the whole evolution vs. creationism debate it is irresponsible not to make the majority opinion clearly known to the public — and to make it clear that it is the opinion of the majority.
#14 Domenico
April 14, 2008

Great thank you !!!
You’re doing a very good job !!^_^

Say hello to Horner for me !! =D
#15 Mike V.
April 15, 2008

I still disagree with smashing bones to make a point. There are skeletons on display in museums (collected decades ago) that don’t have very good documentation. That doesn’t mean I should go in there with a hammer to make a point.

There are thousands of schools across the country that would be absolutely thrilled to get a box of “chum” bones from a museum. It sure would be better to have them in schoolkids’ hands than in museum basements — or worse, in the hands of a paleontologist trying to make a point.
#16 Stephan Pickering
April 16, 2008

Jack Horner’s work is, always, a passion play, so to speak. However, I agree with Phil Currie that, likely, tyrannosaur juveniles hunted for weakening, diseased, and/or young/old prey, then herded them into the waiting killing jaws of their parents or older siblings. The fact remains that, among extant dinosaurs, no taxon exists which is solely an ‘exclusive scavenger’. Moreover, juvenile tyrannosaurs (their bones sometimes misidentified as ornithomimids), based on their skeletal remains, are velociraptorine-like in indicating evidence of being fast, with long arms and hind limbs. Ecosystems — especially predator/prey dynamics and food webs — are far more complex than some realise.
Dinosaurily, Stephan / Chofetz Chayim ben-Avraham
#17 Jud
May 20, 2008

Met Dr. Horner walking through O’Hare airport once. He was patient and friendly in the time allotted – we were walking in opposite directions to catch planes. I asked what he’d been doing lately, and he answered that he was consulting on a movie (which turned out to be Jurassic Park).

I don’t know nearly enough about the topic to argue for or against Dr. Horner regarding the dining habits of T. rex. However, I would like to briefly discuss what seems to me to be an oversimplification of one of Dr. Horner’s points by Sean Craven. Sean writes:

But come on, dude, when you state in a public forum that one of the reasons you think Tyrannosaurs are scavengers [is] because they’re ugly, like hyenas and buzzards…

My (admittedly not exact) recollection of the “ugly” argument is that Dr. Horner proceeds from the premise of the physical characteristics that fit T. rex for scavenging to the conclusion that these would make the animal pretty dang repulsive-looking (and -smelling; IIRC, Dr. Horner’s technical term was “stinky”). Sean’s summary above seems to me to imply a flip of cause and effect.
#18 celinda norvelle
June 24, 2008

I have found a nest of eggs over a year a go, I did not know what they were ate that time, however I sure do know. I know it sounds crazy and if I dont get someone who believes me I think I will go crazy. I have baby embroys that look like little puppies when they are born. many broken eggs. all kinds of legs arms and heads, they looks different from older dino parts, they look like fried chicken, thats how I can tell them apart. Jack your theory sounds right because there is a thick carpet that covers them up. as it rains, pieces break loose and I collect them, if it is not damp I cant get them out. they look like they died ate the same time and piled up on top of each other because babies are not eaten looks to me like thats how they died in a hurry. I see there little expressions there little lips,there little feet and hands are so tiny I have some where there little arms are rapped around the yoks of a broken eggs. the eggs shell somtimes looks like a road map they were so well preserved that in some of them I can see blood veins they were so well preserved. I am a 52 year old women that hikes around alot and rocks are my specialty, so when I started seeing same shape I was interested. if you are interested I promise you wont be sorry. If you would like I can e-mail you a picture for your eyes only of babies. Ps I am an ex dental and I have many teeth,claws, and lots of eggs shell and skin and if I told you what else I have discovered you would think I was crazy for sure, so I will save that one until I can trust you. I have varified on internet many teeth and claws, oh by the way I found this stuff at about 20 or thirty feet deep from where this ranch sits. lots of caves waterfalls.phone number pleas call celinda 512-919-2008
#19 celinda norvelle
June 24, 2008

I have found a nest of eggs over a year a go, I did not know what they were ate that time, however I sure do know. I know it sounds crazy and if I dont get someone who believes me I think I will go crazy. I have baby embroys that look like little puppies when they are born. many broken eggs. all kinds of legs arms and heads, they looks different from older dino parts, they look like fried chicken, thats how I can tell them apart. Jack your theory sounds right because there is a thick carpet that covers them up. as it rains, pieces break loose and I collect them, if it is not damp I cant get them out. they look like they died ate the same time and piled up on top of each other because babies are not eaten looks to me like thats how they died in a hurry. I see there little expressions there little lips,there little feet and hands are so tiny I have some where there little arms are rapped around the yoks of a broken eggs. the eggs shell somtimes looks like a road map they were so well preserved that in some of them I can see blood veins they were so well preserved. I am a 52 year old women that hikes around alot and rocks are my specialty, so when I started seeing same shape I was interested. if you are interested I promise you wont be sorry. If you would like I can e-mail you a picture for your eyes only of babies.
#20 Hai~Ren
March 26, 2009

Oh crap. The spammers are hitting this blog too…
#21 Raymond Minton
March 26, 2009

When Mr. Horner says there’s no evidence that T. rex was an active predator, he’s reversing the burden of proof. Since he’s the one making the extraordinary (and, in my opinion, implausible) claim, the burden of proof is on him to prove it. And remember the Triceratops and Edmontosaurus who were attacked while they were still alive? As I said before, the horse is dead, so stop beating it!
#22 sohbet
March 28, 2009

thank you
#23 Christine
March 30, 2009

I heard from one of my professors that Dr. Horner has reversed his views about T. rex possibly being a scavenger, but that his reversal is just unpublished. Do you think that is possible? (I am writing a paper about this, so obviously Dr. Horner’s views are critical to my research.)
#24 Laelaps
March 30, 2009

Christine; This interview was conducted a little less than a year ago. If Horner has changed his views since the time I asked him about the question I have not heard about it.
#25 Christopher Germany
March 31, 2010

I am not a paleontologist.I’m just an incredibly fascinated person who has found some very interesting bones. The problem is that I can’t get a response from any paleontologists. I would love to know what they are.There are what looks like several animals.There are rib cages,vertibrea,hips connected to legs and feet, and much more. If theres a qualified person out there who still likes new finds please contact me at chrisgermany31@gmail.com and I would love to show them.
#26 mp3 indir
July 13, 2011

I’ve heard all his scavenging arguments before. Just because one animal is different, structurally, from Velociraptor doesn’t mean it didn’t hunt things! Besides that, there ARE fossil instances of T.rex apparently attacking live animals, like the Edmontosaurus with part of its tail bitten off! And then there’s that irritating fact that NOT ONE VERTEBRATE ANIMAL ALIVE TODAY (vultures included) gets its food EXCLUSIVELY through scavenging. Horsepucky. Vultures will eat carrion, sure, but they’ll also go after lizards and small mammals.