If I could be an Allosaurus: The sounds of the Jurassic

Have you ever wondered what it would have been like in the time of the dinosaurs? What they would have looked like and how they would have behaved? What the plants would have been like? Perhaps how hot it would have been, or what smells you could have smelled? What sounds would you have heard as you crouched in a bush and tried not to be found by any large meat-eating carnivores?

Broad-winged katydid (Microcentrum rhombifolium)

A group of scientists from China is filling in one small piece of that complex puzzle. A new study recently published by Gu et al. (2012) in the Proceedings of the National Academy of Sciences names a new stem (or basal) katydid (Archaboilus musicus) from the late Middle Jurassic (Bathovian-Callovian interval at about 165 Ma) of northwest China, namely from the Jiulongshan (or called the Haifanggou) Formation.

Hangingfly (Harpobittacus tillyardi)

This formation is known for several fossil species, although none of them are vertebrates. Its taxa includes the tangle-veined fly Ahirmoneura neimengguensis, the aphid Sinojuraphis ningchengensis, and the hangingflies Formosibittacus macularis, Jurahylobittacus astictus, and Mongolbittacus daohugoensis. The known flora of the formation includes the early flowering plant Xingxueanthus sinensis and the possible early flowering plant Schmeissneria sinensis. Most of these taxa are known from single specimens at the moment, but the preservation is quite exceptional. This preservation means that many features that would normally not be preserved or identifiable are within this formation and in some of these specimens. This leads directly into the new basal katydid Archaboilus musicus.



The type of Archaboilus musicus consists of the part and counterpart of a pair of forewings. Many insects today, including crickets, are able to generate sound using their wings. One of the wings has a row of "teeth", similar to a file. The other acts as a "scraper". One of the co-authors of the study, Montealegre-Zapata, stated that "When they close the wings, the teeth of the file produce vibrations that are amplified as sound by the wing membranes." Many people are currently aware of these sounds. When you are outside, or even inside, and here a cricket "chirping", you are hearing the same actions.

Type of Archaboilus musicus (CNU-ORT-NN2009001PC) showing leftand right forewings. Red arrows in B and D point to area of stridulation and where the noise would been created by the katydid, E and F help show close up versions of the two areas (from Gu et al., 2012).

Stridulation, or the ability to create sounds by rubbing certain body parts together, is well-known in various insects today. With this knowledge in hand, the researchers found that their new insect was preserved well enough to give key details about important morphology of the wings. With this, the researchers conducted thorough comparisons of the forewings of Archaboilus musicus with those of 59 other modern insects. With this comparison, the researchers were able to gain potential insight into something quite incredible and not before really found from the fossil record.

Gu et al. (2012) were able to recreate what this 165 million-year old katydid would have sounded like. Really think about that, a sound not heard for 165 million years has now been recreated. And now you can hear something that the dinosaurs and other animals from that time and region would have heard as well. It may not seem like much, but the ability to recreate that part of the late Middle Jurassic world of northwest China is truly incredible.

The sound was found to be at a low frequency, allowing it to travel relatively far distances. This, combined with the idea that the environment would have been filled with relatively wide-spaced coniferous trees like Araucaria (approximately 1.5 to 20.3 m nearest neighbor distances) and giant ferns (e.g. Angiopteris, Osmunda, and Caniopteris) occupying the lower levels of the forest understory, would have allowed for these low-pitched mating calls to travel much further distances.

Archaboilus musicus reconstructed

The researchers also found that, through comparison with a species of modern katydid, the roughly 4-inch long Archaboilus musicus would have probably been making this call multiple times every second when ready to mate. In essence, the paleoacoustic reconstruction of its call was similar to those of modern crickets, although it would have been of a relatively lower-frequency. In fact, in the movie Jurassic Park, crickets were used for background noise, and it turns out that both sound would have been similar.

Just as interesting as this new insect is what animals would have actually heard these calls while they roamed northwest China all those years ago? While no other vertebrates have been recovered from the Jiulongshan (or called the Haifanggou) Formation, the overlying Tiaojishan Formation does have a diverse assemblage of vertebrates which may have been around at the time of the lyrical Archaboilus musicus and heard its call. As a note, both the Haifanggou and Tiaojishan formations were formerly grouped together as the Lanqui Formation, but that is no longer accepted.

Darwinopterus

In the Tiaojishan Formation (mainly from Laioning), the rhamphorhynchoid pterosaurs are relatively common and include Changchengopterus pani (from Hebei), Darwinopterus modularis, Fenghuangopterus lii, Jianchangnathus robustus, Jianchangopterus zhaoianus, and Qinglongopterus guoi. The istiodactylid pterosaur Archaeoistiodactylus linglongtaensis is also present in the formation.

Along with the pterosaurs, a few other vertebrates are also present in the formation. These include the plant-eating heterodontosaurid Tianyulong confuciusi. The holotype got a lot of recognition due to a row of long, filamentous integumentary structures that appear to be on its back, tail and neck.

Tianyulong confuciusi

Anchiornis huxleyi

Along with the above-mentioned Ornithischian are two theropods that are considered either archaeopterygids or basal deinonychosaurs. Anchiornis huxleyi is a small dinosaur known from several specimens. Xiaotingia zhengi, on the other hand, is known from a single specimen. Anchiornis has gotten publicity lately due to a more in depth look at the coloration of its feathers, giving scientists a better idea of how it may have looked.  

Xiaotingia zhengi

Xiaotingia has gotten recent publicity because in the corresponding phylogeny, Archaeopteryx, long thought to be the "first bird" and a key figure in the evolution of dinosaurs to birds was positioned as a dinosaur rather than a bird. Still, neither of those are the purpose of this post.

Juramaia sinensis

The earliest known placental mammal, Juramaia sinensis, is also found in the Tiaojishan Formation. Juramaia , while not only showing the morphology and transition of a mammal from a metatherian to a eutherian, was also able to push pack this transition 35 million years earlier than had been previously thought. While quite small, this furry little friend would have been scurrying around the trees and doing its best to stay out of the clutches of Anchiornis and Xiaotingia, among other predators that I'm sure have not yet been discovered.

The Tiaojishan Formation has a few invertebrates as well including a few ostracods and a bivalve. There are also a large number of plants present in the formation. For more information on them, try the wiki page for the Tiaojishan Formation.

But, the main point of this post is to try to hear what these dinosaurs, pterosaurs and mammals, among other things, would have heard on a clear night. So, without further ado, I leave you with the movie file below. It is something that I find almost as good as bringing the insect back to life to be able to hear it. You can close your eyes and imagine it is at night 165 million years ago in northwest China. The small Juramaia scurries between your legs, a herd of Tianyulong travel through a few of the trees off to your left, an Anchiornis is sitting in a tree to your right, and you just barely catch a glimpse of a Xiaotingia gliding from a tree in front of you until you lose sight of it. Various pterosaurs can be seen through the trees, and a few land in some trees off in the distance, just visible with the setting sun. And finally you hear a katydid just a little younger than Archaboilus musicus making these calls. The ability to make the picture that much clearer shows just how incredible the science of paleontology, coupled with numerous other fields, can be.

For a different, but very good review of this incredible discovery and study, make sure to check out the post by my colleague David over at the Meniscus!


Reference

Gu J.-J., Montealegre-Z, F., Robert, D., Engel, M.S., Qiao G.-X., and Ren D. (2012). "Wing stridulation in a Jurassic katydid (Insecta, Orthoptera) produced low-pitched musical calls to attract females." Proceedings of the National Academy of Sciences, (advance online publication) doi:10.1073/pnas.1118372109

Alamosaurus and the North American sauropod hiatus

Hello all, I know I've really dropped the ball on this one. It's been far too long. But I'm finally back from SVP in Las Vegas and have a bit of free time to try to catch up and write some things. The meetings went rather well and, as is always the case with these things, I gained tons of information and ideas, and I can't begin to actual use all of them. That leads me in to today's post though. Jeff Wilson and Mike D'Emic, two excellent sauropod paleontologists gave two very good talks on titanosaurs, Alamosaurus, and North America at the meeting, and I will discuss them briefly here, along with some of my questions and ideas.

Image of Alamosaurus from SV-POW blog: http://svpow.wordpress.com/2009/09/02/how-big-was-alamosaurus/

Sphaerotholus (also sometimes called Prenocephale)

First, D'Emic's talk (D'Emic, 2011) focused on much of his Ph.D. research on titanosaurs, and this led into the "27 million year sauropod hiatus' in North America toward the end of the Cretaceous. This was ended, for anyone who isn't aware, by the appearance of Alamosaurus in the Late Cretaceous. D'Emic presented a very interesting phylogeny for the Titanosauriformes. Alamosaurus came out on the end of the cladogram as one of, if not the most, dervied member of the Titanosauria. D'Emic hypothesized that the sauropod hiatus was a result of regional extinction. This regional extinction may have been the result of the infusion of other taxa (such as hadrosauroids), or could have been brought about by other factors, of which we are not certain or aware of at this time. Still, many authors have hypothesized that sauropods, namely Alamosaurus, migrated to North America from South America (where titanosaurs are relatively abundant) or from Asia, where a large number of other taxa are thought to have come from, such as anykylosaurids (Nodocephalosaurus) and pachycephalosaurids (Sphaerotholus, Prenocephale). While we aren't sure yet where they came from, we do know they were here.

The presentation by Wilson (actually presented by D'Emic at the meeting) was mainly discussing whether Alamosaurus is a valid taxon (Wilson and D'Emic, 2011). As reported by Jasinski et al. (2011) Alamosaurus was named based on a nearly complete scapula as the holotype and a nearly complete ischium as the paratype, The material was collected by Reeside in 1921 in the Naashoibito Member of the Ojo Alamo Formation in the San Juan Basin of New Mexico, and named and described by Gilmore (1922).

Fig. 12 from Jasinski et al. (2011), showing A-B, USNM10486 (holotype), left scapula and C-D, USNM 10487 (paratype), right ischium, bars scales  = 10 cm.

These specimens, and this taxon have been the topic of a lot of discussion. Part of the reason for this is the fact that they are somewhat scrappy, and this means that the taxon itself is based on less then ideal material. This also makes it quite difficult to confidently refer other material to Alamosaurus. Nevertheless, the prevailing thought has been that there is a single taxon of sauropod present in North America during the Late Cretaceous. Due to the normalized acceptance of this idea, essentially all sauropod material from North America during this time has been referred to Alamosaurus. Some have conservatively identified some material to Sauropoda indet. or to Titanosauria indet., but this is a small minority. Wilson and D'Emic (2011), however, completed a thorough revision of the type material for Alamosaurus and took this re-investigation further. As was commonly the practive in the early twentieth century, Gilmore (1922) did little to offer some kind of diagnosis for a newly named taxon. Wilson and D'Emic (2011) found that the holotype (and other type) material did contain several autapomorphies, signifying that Alamosaurus is, certainly, a valid taxon.

Herd of Alamosaurus sanjuanensis

Now this was an important step to take. Many authors had used Alamosaurus in phylogenetic analyses and comparisons without being certain of its validity. Some authors, however, have other questions regarding Alamosaurus. Jasinski et al. (2011) did not question its validity, but they did, however, question whether it was being used as a garbage (or waste-basket) taxon. A garbage taxon is when where many taxa or specimens are commonly lumped together without real distinct reasons or definitions. Their thought was that all sauropod specimens were being thrown together even though they couldn't be confidently referred to Alamosaurus. Regardless of whether it was true or not, Alamosaurus was being made the only possible sauropod in North America at this time.

Who's to say there wasn't more than one sauropod taxa in North America in the Late Cretaceous?

Wilson and D'Emic (2011) attempted to address this issue as well. Due to their re-evaluation of the type material, and the material that could then be referred to the taxon through their determined autapomorphies, they were able to come up with a far more thorough diagnosis. Several of the newly referred specimens were far more complete, and this allowed for several confident referrals.This does clear up some of the confusion and some of the problems. It does not, however, clear up all of them. While Wilson and D'Emic attempted to use this as a way of saying that Alamosaurus was, indeed, not a waste-basket taxon, I must thoughtfully disagree.

Although they were able to refer more specimens to Alamosaurus, they were not able to confidently refer all Late Cretaceous sauropod material from North America to Alamosaurus. Their is still plenty of material out their that has not, or can not, be referred. I have seen several specimens of the same element that appear to be significantly different in various aspects, including morphologically. This means that Alamosaurus is still being used, in many ways, as a waste-basket taxon.

I find it somewhat unlikely that only a single sauropod taxon occupied North America from the time of a "sauropod migration" back into North America until sauropods died at at the end of the Cretaceous or just before. It seems far more likely for there to have been more taxa and, assuming they were rare (or more rare) we have not found their remains or have just not been able to positively identify them as such. Wilson and D'Emic (2011) took a very positive first step in this, and their study is very important. I hope to see a complete paper on this in the not too distant future. One thing to remember is that even some of what they do is referral by provenance, so they do have some problems with their study. Still, this may be a good first step in, not only re-evaluating Alamosaurus, but re-evaluating numerous other taxa that face similar or other key problems.

Alamosaurus defending themselves, special thanks to artist for this great artwork

Let me know if you have any thoughts on this though. I would love to know if I am vastly in the minority on this subject, or if other people share my reservations and thoughts.



REFERENCES

D'Emic, M. 2011. Early evolution of titanosuriform sauropod dinosaurs: taxonomic revision, phylogeny, and paleobiogeography. Journal of Vertebrate Paleontology 31(Supplement): 95A. (abstract) 

Gilmore, C. W. 1922. A new sauropod from the Ojo Alamo Formation of New Mexico. Smithsonian Miscellaneous Collections 72: 1-9.


Jasinski, S. E., R. M. Sullivan, and S. G. Lucas. 2011. Taxonomic composition of the Alamo Wash local fauna from the Upper Cretaceous Ojo Alamo Formation (Naashoibito Member), San Juan Basin, New Mexico. New Mexico Museum of Natural History and Science Bulletin 53: 216-271.

Wilson, J. and M. D'Emic. 2011. The validity and paleobiogeographic history of the titanosaur sauropod Alamosaurus sanjuanensis from the latest Cretaceous of North America. Journal of Vertebrate Paleontology 31(Supplement): 215A. (abstract) 

Coelophysis biomechanics and the early part of a '"career"

In sticking with a theme of some of my papers that have come out recently, I would like to briefly talk about Coelophysis biomechanics. Coelophysis, in case some of you aren't aware, is, at least in my knowledge, a fairly well known early theropod dinosaur from the Late Triassic of New Mexico (and Arizona). With that said, I started my college career looking to follow in the footsteps of my father and uncle and become a chemist. I learned, after a little over two years (yes, it probably shouldn't have taken me quite that long) that I didn't really want to spend the rest of my life being a chemist. I bounced around for a semester or two before I took a gen ed course regarding dinosaurs and mass extinctions. As almost all young boys do, I was fascinated with dinosaurs and extinct animals. I never thought of pursuing a career till I took that course and talked things over with the instructor, a paleobotanist (Peter Wilf). He managed to convince me to pursue paleontology (geology mainly). Luckily, a vertebrate paleontologist had started there not long before (Russel Graham), and he was very accommodating with me on whatever I wanted to work on. So, for my senior thesis I conducted a project on the biomechanics of Coelophysis.

Coelophysis bauri

Coelophysis is so "famous" because of the sheer number of fossils of this animal that have been found. Almost all (if not all) of them are from a single locality, Ghost Ranch in northern New Mexico. Hundreds of individuals have been recovered, but many more are still there. The quarry has been closed, at least for the time being, but there is always hope that it may be re-opened. I suppose that looking at more of Coelophysis is not that interesting to many people, but a huge accumulation of individuals could help with paleobiologic studies and community structure, or perhaps tell us innumerable other things of this interesting little meat eater.

For my study though, I was looking for complete, or nearly complete, lower jaws. I treated the jaws as a lever, and the amount of bone at any one point in that lever can allow someone to see how strong the jaw is. The more bone present, the stronger the jaw. Of course, length and position also play a factor. I won't go into the methods too much, for that you can look at the paper itself (Jasinski, 2011).

Varanus komodoensis (Komodo dragon)

Dromaeosaurus skull

What was found though, was that the mandible of Coelophysis was most similar to Varanus komodoensis (Komodo Dragon) and dromaeosaurids. This suggests that Coelophysis may have hunted in ways similar to both the Komodo dragon and dromaeosaurids.

This is interesting by itself, but I was also able to look at the skull of a juvenile. While it may bot be especially surprising, the juvenile showed a strength profile incredibly similar to the adult Coelophysis. This suggests that juvenile Coelophysis were hunting in ways similar to the adults. This doesn't mean that they would be taking the exact same prey, but both parents and adults would have been hunting things (and these things would have been larger than insects).

The thought is then, if juveniles had to hunt on their own and take their own prey, that Coelophysis was probably not a precoccial animal and was mainly solitary. Others have thought this, but this is another method of showing it. Other techniques and studies are needed to confirm or deny this idea.  Coelophysis may be more deadly then previously expected though.

Coelophysis bauri skull and lower jaws

Take a look at the Beasts Evolved blog page as well to get another brief look at this paper and bit of different information on it and the paleobiology of Coelophysis.

So, that was my senior thesis, and, with a few add-ons, was recently published in the New Mexico Mexico Museum of Natural History and Science Bulletin. If you would like a copy, feel free to email me (sej139@yahoo.com). Otherwise, I am still early in my potential paleo career, so there should be plenty more to write about as I go.

Reference
Jasinski, Steven E. 2011. Biomechanical modeling of Coelophysis bauri: Possible feeding methods and behavior of a Late Triassic theropod. New Mexico Museum of Natural History and Science Bulletin 53: 195-201.