We’ve reached a milestone: episode 100! Thank you so much to all our patrons on Patreon! We hope you enjoy this very special episode and please keep a lookout for the extra special rewards we promised. We are so lucky to have this podcast and meet such wonderful dinosaur enthusiasts, and we owe it all to our listeners.
On that note, in our 100th episode, we had the pleasure of speaking with Dr. Emanuel Tschopp, a postdoctoral fellow at the University of Turin in Torino, Italy, as well as the author of numerous papers, one of the most well known being A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda), a study published in 2015 about 81 sauropod specimens, which found Brontosaurus to be a valid genus again. You can find more of Dr. Tschopp’s work at https://www.researchgate.net/profile/Emanuel_Tschopp.
Episode 100 is all about Brontosaurus, a sauropod whose name means “thunder lizard” and one of the earliest named dinosaurs that wasn’t considered to be a valid genus for about 100 years.
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In this episode, we discuss:
- The dinosaur of the day: Brontosaurus
- Name means “thunder lizard”
- Type species is Brontosaurus excelsus, which Marsh named in 1879
- The species name excelsus means “noble” or “high”
- Brontosaurus lived about 155 to 152 million years ago, and fossils have been found in Wyoming and Utah
- For a long time was considered a junior synonym of Apatosaurus, and the original species Brontosaurus excelsus was reclassified as Apatosaurus excelsus in 1903
- The Morrison Formation was the center of the Bone Wars, and at the time lots of dinosaur descriptions were rushed
- Marsh named Apatosaurus in a two-paragraph article for the American Journal of Science in 1877, and then wrote a more detailed article in 1879 with a sketch of Apatosaurus‘ pelvis, shoulder blade, and vertebrae
- In 1903, Elmer Riggs said Brontosaurus was too similar to Apatosaurus, and he called Brontosaurus excelsus, Apatosaurus excelsus. Apatosaurus was named first, so Brontosaurus became a synonym. However, Henry Fairfield Osborn decided to label the skeleton in the American Museum of Natural History Brontosaurus, even though he opposed Marsh and Marsh’s taxa
- The AMHN Brontosaurus skeleton is the reason for so much controversy the last 100 years or so (scientists thought it should be Apatosaurus, but the public knew about Brontosaurus)
- The skeleton was unveiled in 1905 at the AMNH and was the first mounted sauropod. It was a mostly complete specimen, but it was missing feet, lower leg, shoulder bones, and tail bones (the tail was mounted with too few vertebra, but according to what Marsh thought it should be). The skull was also based on “”the biggest, thickest, strongest skull bones, lower jaws and tooth crowns from three different quarries”, which most likely came from a Camarasaurus (only other sauropod at the time with known skull material). Adam Hermann couldn’t find any Brontosaurus skulls so he had to hand sculpt a skull to stand in. Osborn made a note in a publication that Hermann’s skull was “largely conjectural and based on that of Morosaurus” (now Camarasaurus)
- An Apatosaurus skull was found in 1909 near a skeleton that was found to be an Apatosaurus specimen. The skull was similar to Diplodocus‘ skull, and so many believed it was an Apatosaurus skull (though Osborn and others rejected this). William H. Holland, the Douglass and Carnegie museum director, believed it was an Apatosaurus skull, but he didn’t put a head on the mount at his museum, possibly because he was waiting for someone to find an articulated skull and neck. After he died in 1934, museum staff put a Camarasaurus skull on their mount
- The first Apatosaurus with an articulated skull was found in 2011
- In 1931, the Yale Peabody Museum created a unique skull, where they based the lower jaw on a Camarasaurus, and gave it forward-pointing nasals, instead of basing it solely on Camarasaurus
- In the 1970s, John Stanton McIntosh and David Berman redescribed Diplodocus and Apatosaurus skulls, and found that Holland was right, and that Apatosaurus, and Brontosaurus, had a skull similar to Diplodocus. They also reassigned many Diplodocus skulls as Apatosaurus.
- In 1979, Carnegie mounted the first Apatosaurus skull on a skeleton, then AMNH did the same in 1995 (also relabeled their skeleton Apatosaurus excelsus and corrected the tail
- British-Portuguese research team did a joint study in 2015 that found Brontosaurus was a valid genus, separate from Apatosaurus (though not all paleontologists agree)
- “A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda)” by Emanuel Tschopp, Octavio Mateus, and Roger B.J. Benson, published in April 2015
- The 2015 study also found that two species that used to be considered Apatosaurus and Eobrontosaurus were now Brontosaurus: Brontosaurus parvus and Brontosaurus yahnahpin
- Brontosaurus parvus was first described as Elosaurus in 1902, by Gilmore and Peterson. Then it was assigned to Apatosaurus in 1994, and then to Brontosaurus in 2015. Includes a partial juvenile skeleton, a nearly complete skeleton that’s mounted at Brigham Youn University, and another partial skeleton
- The oldest species is Brontosaurus yahnahpin, found in Wyoming in the Morrison Formation (lived about 155 million years ago). It was 69 ft (21 m) long, and described in 1994 by James Filla and Patrick Redman (who named it a species of Apatosaurus). The species name means “breast necklace” because it has pairs of sternal ribs that look like hair pipes worn by the Lakota tribe
- Bob Bakker said in 1998 that it was more primitive than originally thought, and named it Eobrontosaurus (Greek word “eos” means dawn), which again is now back to Brontosaurus, according to the 2015 study
- The original intent of the 2015 study was to revise the family tree of diplodocids
- Most diplodocid species were described in the late 1800s and early 1900s
- Many holotype specimens were incomplete and fragmentary
- The study included “81 operational taxonomic units, 49 of which belong to Diplodocidae”
- The 2015 study is almost 300 pages long, and it analyzed 477 different physical features of 81 sauropod specimens, and took 5 years to do (and visits to 20 museums in Europe and the U.S.)
- In the 2015 study, they used algorithms to compare traits, and if more than 20% of the traits were different, they classified the bones as their own genus
- Tschopp said, “The border between different species and different individuals within a species were progressively much lower,”
Tschopp said, “We were very surprised when we got these results that Brontosaurus was valid again.” And they had Roger Benson, from Oxford University, verify their results
- Roger Benson said, “The differences we found between Brontosaurus and Apatosaurus were at least as numerous as the ones between other closely related genera, and much more than what you normally find between species,”
- Brontosaurus coming back has been often compared to Pluto, with many people hoping Pluto will be classified as a planet again
- “It’s a nice example of how science works. A new finding can overturn more than 100 years of beliefs,” said Emanuel Tschopp
- “We knew it would be a major finding because Brontosaurus is such a popular name,” Tschopp said. “I’m pretty sure there will be a scientific discussion around this. I hope there will be. That’s how science works.”
- Tschopp said this study could not have been done 15 years ago, but so many dinosaurs similar to Apatosaurus and Brontosaurus have been found recently, which makes it easier to reexamine
- Three valid species of Brontosaurus (according to the 2015 study): Brontosaurus excelsus, Brontosaurus parvus, Brontosaurus yahnahpin
- 2015 found that Elosaurus and Eobrontosaurus are synonymous with Brontosaurus
- 2015 study said Brontosaurus amplus was an invalid proposed species (and would become Brontosaurus excelsus)
- Marsh named Brontosaurus amplus in 1881, but it’s now considered to be a synonym of Apatosaurus excelsus (Gilmore said it in 1936, McIntosh said it in 1990 and 1995, Upchurch, Tomida & Barrett said it in 2004, though most studies also said there needed to be a more detailed assessment)
- 2015 study said that Brontosaurus had “1) a longer than wide base of posterior dorsal neural spines (279-0, unique among Apatosaurinae), (2) the area on the scapula posterior to the acromial ridge and the distal blade is excavated (365-0, unique among Apatosaurinae), (3) the acromial edge of the scapular blade bears a rounded expansion at its distal end (367-1, unique among Apatosaurinae), (4) the ratio of the proximodistal length/transverse breadth of the astragalus is 0.55 or greater (451-1, unique among Apatosaurinae).”
- 2015 study said “Brontosaurus excelsus can be diagnosed by the following autapomorphies: (1) absence of a median tubercle in posterior cervical and anterior dorsal, bifid neural spines (210-0*, unique among Diplodocidae), (2) orientation of the tuberculum of mid-dorsal ribs follows the straight direction of the rib shaft (285-1*, unique among Apatosaurinae), (3) the posterior end of mid- and posterior caudal neural spine summits lies more or less straight above the postzygapophyses (343-1*, unique among Apatosaurinae), (4) the ratio of iliac blade height above the pubic peduncle to its anteroposterior length is 0.40 or greater (405-1*, unique among Apatosaurinae), (5) the highest point on dorsal margin of the ilium lies anterior to the base of the pubic process (410-1*, unique among Apatosaurinae), (6) presence of a large nutrient foramen opening on midshaft anteriorly on the femur (434-1*, unique among Apatosaurinae), (7) absence of a laterally directed ventral shelf on the astragalus, which underlies the distal end of the fibula (455-1*, unique among Apatosaurinae).”
- According to Emanuel Tschopp, Brontosaurus has a higher, less wide neck than Apatosaurus. “So although both are very massive and robust animals, Apatosaurus is even more extreme than Brontosaurus.”
- Interesting because Brontosaurus means thunder lizard, and Apatosaurus means deceptive lizard
- Paul Barrett, from the Natural History Museum in London, said ““It’s the biggest study on this family, they marshal a lot of evidence and make a very good case” and “It’s taken us a long time to convince people that we shouldn’t be using the name ‘Brontosaurus’, Just as we’ve got to that point, it looks like we’re going to have to turn around and say ‘Actually, it’s alright again’.”
- Not everyone is fully convinced yet though. Brian Switek said the problem is there is no standard for choosing which traits are significant, so there’s still some subjectivity when classifying genera. This may not be settled until a Brontosaurus skull is found
- Kenneth Carpenter, from Utah State University’s Eastern’s Prehistoric Museum, said the fossil that Apatosaurus is based on hasn’t been described in detail, and should have been in order to be compared to Brontosaurus. He said, “So is Brontosaurus valid after all? Maybe. But I think the verdict is still out.”
Paleontologist Donald Prothero who said, “Until someone has convincingly addressed the issue, I’m going to put “Brontosaurus” in quotes and not follow the latest media fad, nor will I overrule Riggs (1903) and put the name in my books as a valid genus.
- Brontosaurus was quadrupedal, with a long neck, a long, whip-like tail, and forelimbs that were a little shorter than its hindlimbs
- Originally, Brontosaurus (and other sauropods) were thought to be too heavy to walk on land, so it was thought they lived partly in water (this is not true)
- If Brontosaurus were completely submerged in water, it would not have been able to breathe, because the water pressure on its lungs would be too much
Most sauropod fossils are found in dry, inland areas
- Like other sauropods, Brontosaurus had neck vertebrae that was bifurcated (had paired spines, which meant it had a wide, deep neck)
- Its neck had air sacs, to help make it lighter
- Brontosaurus also had tall spines on its vertebrae, like Apatosaurus
- Had long ribs compared to other diplodocids, so they had very deep chests
- Had stout arm bones, and a large claw on its forelimb, and three toes on each foot (each toe had a claw as well)
- Why there’s a claw on the forelimb is unclear. It may have been for defense, though it’s not the best size or shape for that. It may have been used for feeding, or used to grasp things like tree trunks when rearing
- Brontosaurus was originally thought to have a short tail
- It could crack its tail, to signal to others, show dominance, or warn predators such as Allosaurus, Torvosaurus, or Ceratosaurus
- Brontosaurus excelsus is the largest species and weighed 15 tons, and was 72 ft (22 m) long
- Adult Brontosaurus parvus is estimated to weigh 14 tons
- Sauropod trackways show that they moved as fast as 12-19 mph (20-30 kph), and moved on average 12-25 miles (20-40 km) per day
- Had a small head
- Swallowed stones to help digest
- May have reared up to reach high plants or fight for mates
- Brontosaurus may have been solitary
- Brontosaurus has been featured in film, ads, stamps, and lots of other media
- Gertie the Dinosaur, Winsor McCay’s animated film (one of the first) is a Brontosaurus
- Brontosaurus and Allosaurus battled in the 1925 silent film The Lost World
- Brontosaurus is also in the 1985 movie Baby: Secret of the Lost Legend
- Brontosaurus is also the logo of the Sinclair Oil Corporation (it’s green)
- A full sized Brontosaurus model of Sinclair’s Brontosaurus was at the 1964-65 New York World’s Fair
- In 1989 the U.S. Postal Service made four dinosaurs stamps, and one was Brontosaurus (which people complained as “fostering scientific illiteracy”). The Postal Service said in Postal Bulletin 21744, “Although now recognized by the scientific community as Apatosaurus, the name ‘Brontosaurus‘ was used for the stamp because it is more familiar to the general population.” They also said “”[s]imilarly, the term ‘dinosaur’ has been used generically to describe all the animals [i.e., all four of the animals represented in the given stamp set], even though the Pteranodon was a flying reptile [rather than a true ‘dinosaur’],” which people did not complain about. Stephen Jay Gould, a paleontologist, wrote an essary and book partly based on this (the part “Bully for Brontosaurus” says, “Touché and right on; no one bitched about Pteranodon, and that’s a real error.” (Though Gould did agree that Brontosaurus be a synonym for Apatosaurus
- Part of the family Diplodocidae (which includes Diplodocus, Supersaurus, Barosaurus)
- Also part of the subfamily Apatosaurinae (includes Apatosaurus)
- The family Diplodocidae means “double beams”
- The Diplodocidae clade has 12-15 species that lived in the Late Jurassic and Early Cretaceous
- Compared to titanosaurs and brachiosaurs, dipodocids were slender and long, with short legs, and their back legs were longer than their front legs
- Many may have had spines on its back
- Very long necks, may not have been able to lift heads as high up as other sauropods
- Had small heads and peg-like teeth
- Probably didn’t chew, but swallowed gastroliths to digest their food
- Had long, whip-like tails that they could snap
- Diplodocidae was originally known as Amphicoelidae (named by Edward Cope in 1878), but became a forgotten name; Charles Marsh also named the family Atlantosauridae back in 1877, but that also became a forgotten name (nomen oblitum)
- Fun fact: Back in January we mentioned that the “Dinosaur Genera List” listed 1007 dinosaur genera (which is at the higher end of valid genera counts) The list was just updated and now includes another 20 genera, bringing the total to 1027 (Both numbers include Brontosaurus)
This episode was brought to you by:
The Royal Tyrrell Museum. The Royal Tyrrell Museum is located in southern Alberta, Canada. One of the top paleontological research institutes in the world, the entire museum is dedicated to the science of paleontology. It’s definitely a must see for every dinosaur enthusiast. More information can be found at tyrrellmuseum.com.
For those who may prefer reading, see below for the full transcript of our interview with Dr. Emanuel Tschopp:
Sabrina: Dr. Emmanuel Tschopp is a postdoctoral fellow at the University of Turin in Torino, Italy, as well the author of numerous papers. One of the most well known is “A specimen level phylogenetic analysis and taxonomic revision of Diplodocidae, Dinosauria, Sauropoda,” a study published in 2015 about 81 sauropod specimens, which found Brontosaurus to be a valid genus again, and making him one of my favorite people. And he is currently working with lizards trying to understand the methodology and phylogeny as well.
Dr. Emmanuel Tschopp: Hello.
Sabrina: Hello, how are you?
Dr. Emmanuel Tschopp: Good and you?
Sabrina: Good, how did you first become interested in dinosaurs and decided to become to go the paleontology route?
Dr. Emmanuel Tschopp: Well there was—actually when I was a kid, as most of these dinosaur paleontologists, we had dinosaurs at school and at the same time actually there was a new museum opening close to where I grew up. And then they showed dinosaurs from North America. And so the interest that started elementary school just got fed more I guess at the museum, then it showed me that it was possible to sort of do actually paleontology in Switzerland as well.
Sabrina: Wonderful. Were there any particular dinosaurs that stood out to you?
Dr. Emmanuel Tschopp: Not really.
Sabrina: Just in general?
Dr. Emmanuel Tschopp: I guess just all of them very exciting.
Sabrina: Yeah, so how did you decide to do the study that came out last year where you analyzed the 81 sauropods specimens, like what prompted that?
Dr. Emmanuel Tschopp: This also has to do with that museum close to where I grew up, because the museum means it’s called [inaudible 00:01:50] Museum [inaudible 00:01:54]. And it had its own dig sites in Wyoming, which is on the famous Cava [ph] Ranch where the American museum also dug in the 30s. And from there they had the big collection of diplodocid sauropods.
And looking into that with my soon to become PhD supervisor back in 2009, we saw that there was still a lot of work to do even though most of it seems to or seemed to have been known already. And with these new specimen sets have never been studied in detail at the [inaudible 00:02:40] Museum we could actually try to do a re-analysis of the systematics and taxonomy of this group.
Sabrina: So how many places did you end up going to study these specimens? I know the paper mentions a few different continents, so where specifically did you go?
Dr. Emmanuel Tschopp: Well I went to numerous museums in Europe and in the United States. I think they were around 20 or so different museums and the university collections that I visited. And of course the most important ones are the American Museum in New York, the Peabody Museum in New Haven, the Carnegie Museum in Pittsburgh, but also the Museum für Naturkunde Berlin in German and other big institutions.
Sabrina: Wow, yeah so then you spent probably a good chunk of time just travelling, right? Getting to all these museums?
Dr. Emmanuel Tschopp: Yes, that’s true.
Sabrina: How long did it take to complete the study?
Dr. Emmanuel Tschopp: It was the main part of my PhD. So basically I started collecting data for this in 2010, and published in 2015. So it was not the only thing I did, but yeah the first collection of data was five years before publication.
Sabrina: Wonderful and then how big was the team who worked on this with you?
Dr. Emmanuel Tschopp: Well I did most of the collecting myself, but there was obviously my PhD supervisor who also moved in the development and methodological issues. And then about a year before publication when they went on—so revisions the entire project, we invited Roger Benson from the University of Oxford to contribute as well—the very method that he actually developed and applied to Plesiosaurus to try to understand which specimen actually belonged to what species, and where to define those boundaries between individuals and species in general.
Garret: Well that’s interesting. I know on the paper you talk a lot about like the number of vertebra or vertebrae in the neck of some of the sauropods. Is that kind of a thing that he was using with the Plesiosaurus too?
Garret: Well in that methodology he used it was more to understand how many or how much difference the single specimens are, and how much variability we can accept within the species, or when we have to decide that they should be considered different genre. So he did not actually go out to specific, single specific features like the number of vertebra.
Sabrina: So was the most surprising find about Brontosaurus or were there other surprises in the study?
Dr. Emmanuel Tschopp: There were two big surprises. One is of course Brontosaurus which is unless you did not expect in the beginning, but the other big surprise was also that like applying these kind of numerical rules to the entire group of diplodocids. We also saw that the Portuguese species [inaudible 00:06:22] was actually not different enough from the North American [inaudible 00:06:29] to be a separate genus. So earlier studies already found the two as a sister [inaudible 00:06:39] which means they are the most closely related, or they are more closely related to each other than to any other diplodocid. But our analysis was to first to show that these differences were not so many, and therefore to state that [inaudible 00:07:01] analysis should actually be a species of Supersaurus.
Dr. Emmanuel Tschopp: And this is the first sauropods where we have convincing evidence that the same genus was present in the late Jurassic of North America and Portugal.
Sabrina: Oh wow.
Dr. Emmanuel Tschopp: So yeah this was kind of nice, but surprising also.
Sabrina: Sure, yeah it’s very far away from each other.
Dr. Emmanuel Tschopp: Well yeah it was closer back in time.
Sabrina: Yeah but still.
Dr. Emmanuel Tschopp: And actually there is evidence for Sarcosaurus or Allosaurus, so in other dinosaur groups we have sharing the genre. But there was no good evidence yet for sauropods. Just yeah with our study that changed.
Sabrina: So how exactly did you analyze all these specimens? Once you go to the museum, is it a matter of just kind of carefully looking or CT scans or something else?
Dr. Emmanuel Tschopp: It was more just a matter of very careful looking. We created this matrix, it’s called—it’s a list of characteristics in the bones of the entire skeleton. And we found almost 500 of those characteristics in the end that we have to check in every single specimen. So it was really just going through all the collections and trying to understand first which bones actually belonged to a single individual, which was already not such an easy task.
And then with this we could just check within this list if these characteristics were present or not in those individuals that I was studying. And this list could then be fed into a software which is called DNT, and that software could calculates actually the relationships between the individuals in this case. Usually this is done with species, but in our case it is with individuals exactly, because we wanted to test which specimen belongs to what species?
Sabrina: So I read that in an article I believe you said the study couldn’t have been done 15 years ago, but now we’ve had their most enough specimens to study.
Dr. Emmanuel Tschopp: Yeah.
Sabrina: So yeah I guess I’m wondering if we can expect these kinds of big studies more in the future because it seems like we keep finding more and more specimens of…
Dr. Emmanuel Tschopp: Yes definitely. The problem was before that most of these individual specimens were extremely incomplete, and especially the reference specimens for the single species. So every species has its own reference specimen which is tied to the specific name. And some of them only preserved tail vertebrae, other ones only preserved teeth, some preserved only some collection of leg bones and obviously these are not directly comparable.
So then we just try to understand the diversity based on these specimens. We cannot really say anything; they could all be the same thing. But with new and more complete specimens that actually preserve at least parts of a single individual that overlap with several different incomplete specimens, we can tie them together.
And in the last 15 years more and more of these complete specimens have been dug up. And especially diplodocids; its collection at a museum in Switzerland was very important, because they had three or four really nice episodes of specimens that provided this kind of backbone of the analysis where incomplete specimens could be compared through those with each other indirectly.
Sabrina: Yeah and so reading a number of articles it seems like not everybody is fully on board with the findings from the study. I just want to—I was curious what do you think of that? Like is it, I guess if we can expect more of these studies maybe that will help get people more on board or I don’t know, we see some sort of debate.
Dr. Emmanuel Tschopp: Yeah there is, it has been quite a big debate since publication already like very fast after. It’s interesting to me, I’m very looking forward to seeing more and more papers coming out on this, and to be like in this discussion. It is debated mostly because of these propositions of numerical approaches to decide where to put boundaries between species and genre.
This is or this has been done in the past more subjectively, we tried—its numerical approach is to be a bit more objective and repeat those so that people can take our analysis and do their own stuff. And test also the methodologies that we used, but yeah because this is kind of a new approach there is obviously a discussion around it, and yeah we can see where it brings us.
These taxonomic changes are actually like almost daily verticals of scientists at least of people working with systematics. So it was not so surprising to find or to have changes in taxonomy when doing such an extensive work, because that’s interesting because brontosaurus was in there and it’s such a popular dinosaur and a genus so that everybody just was happy to have it back.
Sabrina: It’s true.
Garret: Yeah so what, I think I remember a few of the details, but what were the differences you found with Brontosaurus that you decided that it was significant enough to warrant its own genus?
Dr. Emmanuel Tschopp: Well the most important thing here is that it’s not like single important features that distinguish them. It’s the number of features that are numerous enough to allow a distinction at generic levels so that the two genre are actually different. There are differences in the shoulder vertebra and some tail bones and then some foot bones.
These are probably not really visible, probably not really visible in the living animals that can be seen in the bones themselves as kind of anatomical details, but some of these details allow it to distinguish them as genre.
Garret: Okay, so it’s really more like a question of how many different mutations would happen, and then you can kind of tell how long ago they would have had the spilt, is that kind of the idea?
Dr. Emmanuel Tschopp: Yeah kind of, of course we don’t know exactly how many mutations had to happen for about the kind of difference in the bone. This is almost impossible to know, but the idea behind it was basically the same. And methodologies like this are used with molecular phylogeny is also very—people today study living animals, and try to understand how much or how different it should be to be called different species and different genus. Yeah it’s just an assessment of variability and how much we can, how much has been interpreted in the past as enough for different species, and applying this more universally to the entire group of diplodocids.
Garret: Yeah, I like that approach, and I know typically the best you can do is have consistency within a specific group like a subset of sauropods or hadrosaurids or something. Because then even between groups like the difference between a genus in hadrosaurids might be much more specific than a genus within titanosaurs or something.
Dr. Emmanuel Tschopp: Yeah this is actually a very interesting point because it’s not just like a methodological issue, but it’s also a historical issues. Because in some groups researchers just tended to have or to combine or to allow more variability for a species than in other groups, and taxonomy is about stability. So to some extent we also have to think about these historical interpretations, and merge them into consistent interpretations.
Garret: Is that with a little a lot of the blow back about Brontosaurus just a fact that it’s not been used for a long time?
Dr. Emmanuel Tschopp: Probably, there is another reason also because if you actually look at the phylogenetic trees that we got, Brontosaurus is still the closest genus to Apatosaurus. So actually just based on what you see in the tree, you could also say that the two branches of the tree with Apatosaurus and Brontosaurus can still be regarded as belonging to a single genus, because there is nothing in between that should be something else. So it is really just these numerical approaches that we proposed here, and the idea of consistency of the number of changes that was usually considered enough on the prediction of genre in the Diplodocus part of the tree, but apparently not in the Apatosaurus part of the tree.
Garret: That’s funny.
Dr. Emmanuel Tschopp: So I kind of found that strange and yeah applying a consistent variability also in Apatosaurus, Brontosaurus came up as a different genus.
Garret: And you had I think three different species of Brontosaurus two of Apatosaurus in the end, am I right about that?
Dr. Emmanuel Tschopp: Yes, the number of species is actually the same as the one that we had before.
Garret: Okay that’s what I thought. So did any species get synonymized or split out in your study?
Dr. Emmanuel Tschopp: Not in Apatosaurus, no.
Garret: Okay, but they did in other parts of the analysis?
Dr. Emmanuel Tschopp: Well we found some to be invalid like Diplodocus [inaudible 00:19:18] is just a set of teeth. So there is no diagnostic features in there, also Diplodocus longus which is basically a series of tail vertebrae but only two of them are reasonably complete. And also there it’s not really a diagnostic character that you could use to define the species. So these two were invalid, and the analysis also confirmed earlier interpretations of Seismosaurus being just the species of Diplodocus. So this synonymous which was proposed before already was confirmed by our analysis.
Sabrina: Yeah it’s really interesting. So I’m curious because I saw some of your other papers have to do with Camarasaurus or other sauropods. I was just wondering was that your focus for your PhD, sauropods in general?
Dr. Emmanuel Tschopp: No the focus was really diplodocids. The work in Camarasaurus I did in the first postdoc just after the PhD. I still have to gather around to finish that up and publish that entire phylogeny. I hope to get that done soon as well.
Sabrina: That’s great, I’m a big fan because I’m on the group of people who were excited when you said Brontosaurus is a valid genus again, so that’s my favorite.
Dr. Emmanuel Tschopp: Okay happy to be of service.
Sabrina: Also so we just want to ask what is your favorite dinosaur personally?
Dr. Emmanuel Tschopp: That’s a very good question. I think I don’t really have a favorite species, I find sauropods cool because, mostly because I specialize in most of them. Obviously I find the one even cooler that I describe myself, it’s called [inaudible 00:21:28]. But yeah that’s more like, not because of the animal it is, but because it is kind of my dinosaur baby.
Sabrina: That’s excellent too.
Garret: That’s cool when did you discover that one or name it?
Dr. Emmanuel Tschopp: That was also part of my PhD. It was one of the first diplodocid specimens I looked in detail at. I studied in detail at a museum in Switzerland. And it was published in 2012 online.
Dr. Emmanuel Tschopp: And 2013 in print.
Sabrina: Yeah that’s great.
Garret: I think that will be my favorite dinosaur, if I found one too, regardless of what it was.
Dr. Emmanuel Tschopp: Yeah, it’s quite logical.
Sabrina: So you mentioned earlier that you are currently working with lizards and doing sort of the same thing that you did with the diplodocids. Can you talk a little bit about that?
Dr. Emmanuel Tschopp: Yeah sure, so I’m trying to perfectionize, can you say that?
Dr. Emmanuel Tschopp: The methodology of specimen that was phylogeny mostly because it has not really been tested with living animals. So this test that I’m doing right now, and in these living lizards I know the species or the skeletons I’m studying belong to. So I can just adapt all the different factors in the methodology to get the tree as I would expect the tree should be. And then obviously apply it again to process in future.
Sabrina: Yeah I was going to say if, once you’ve…
Dr. Emmanuel Tschopp: It looks purposeful.
Sabrina: Yeah and once you’ve perfected it too do you think more people will come to accept this new way of looking at dinosaurs?
Dr. Emmanuel Tschopp: Well there are already many more studies like this of different sauropods, not sauropods, dinosaur groups. So it’s a methodology that is being used more and more in birds paleontology as well. It’s actually what is being used almost always in biology. So if you have molecular phylogenies of living animals, like 99% of them are specimen level. And so it’s interesting also from this point of view to apply the same or a similar approach to fossils also.
Dr. Emmanuel Tschopp: But these analyses in biology are based on DNA and not on the bones and so if you don’t really know how the methodology behaves when studying bones. And that’s the main goal here with the lizard approach.
Sabrina: Yeah that makes sense, cool. Well thank you so much for talking with us today we are really excited.
Dr. Emmanuel Tschopp: Well thanks for the invitation, I’m glad to be the 100 episode’s topic.
Sabrina: Oh yeah us too. Like I said Brontosaurus is my favorite.
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