Fruitadens: how small can a dinosaur get?

Dinosaurs have become known, for the most part, as huge reptiles from the past. Huge carnivores like Tyrannosaurus rex would have been chasing hadrosaurs, like Parasaurolophus, and ceratopsids, like Triceratops. Gigantic battles may have been waged, with the outcome being life or death struggles. While this paints an incredible picture and is commonly what people think of when hearing the word "dinosaur", many others realize that dinosaurs could also be quite small. Velociraptor, of Jurassic Park fame, was not actually very large, with adults measuring 6-7 feet long (including the tail), protoceratopsids (small relatives of Triceratops) were only roughly sheep-sized and grew to about 6 feet with their tails included. While these are slightly more well-known, various other dinosaurs stayed diminutive compared to the larger things around them.

In the Late Jurassic (around 150 Mya) of the USA, famous dinosaurs such as Allosaurus, Stegosaurus, Apatosaurus (= Brontosaurus), and Brachiosaurus were roaming the American west. Running around their feet, and doing their best not to get trampled, was a tiny dinosaur named Fruitadens haagarorum, named by Butler and colleagues in 2010). Fruitadens was a tiny, plant-eating dinosaur from the group known as heterdontosaurids. 

Artist’s reconstruction of Fruitadens ( by Smokeybjb, and licensed under Creative Commons Attribution-Share Alike 3.0 Unported license.)

Heterodontosaurids were a group of plant-eating ornithiscians related to iguanodontids (like Iguanodon) and hadrosaurids (like Parasaurolophus and Edmontosaurus), among others. These dinosaurs were commonly fairly small, and had "fangs" towards the front of their mouths.You should be able to see the fangs if you look close enough at the reconstruction. They actually get their name from their strong heterodont dentition. Even so, their morphology is relatively generalized, suggesting more of an omnivorous lifestyle, with plants, insects, and some other small organisms making up the majority of their diets.

Fruitadens was named based on a few individuals (4), but the holotype consists of incomplete jaws, several vertebrae, and partial hind limbs of a nearly full grown individual. This was sufficient, however, to determine that it was, indeed, something unique and new.

Reconstructed skull of Fruitadens (Butler et al., 2012)

Fruitadens was estimated by Butler et al. (2010) to have only been about 28 cm long (less than a meter) and weighed less than 1 kg (less than 2 lbs)! That size estimate is quite incredible, especially for a dinosaur that is thought to be nearly full-grown. Overall size would have probably not changed at all, or at least very little, once it became fully mature!

Full-size Fruitadens haagarorum model with co-author Luis Chiappe (from AP).

But why bring this up now if this dinosaur was named in 2010? In the original publication, Butler et al. (2010) were unable to go into much detail regarding the description and morphology of this new taxon. But a new, thorough study just published by Butler et al. (2012) has given this small dinosaur its descriptive due. The new study seeks to document this dinosaur in great detail, giving new information not only on Fruitadens, but also on the whole heterdontosaurid family of dinosaurs. This study helps us understand a group of dinosaurs that were not very well known before, and helps clarify a picture that can seem somewhat blurry at times (or all the time...).

This seems to be an excellent example of a taxon that was named in a relatively short paper, but then had a follow-up study to give us a much clearer picture of exactly what it was/is. Too often taxa (not just dinosaurs) are named in short papers or with short blurbs. Little detail is given, and sometimes proper diagnoses are not even provided. I can't tell you how many times I have come across taxa and, when going to the original publications, I find little information other than the name itself. And, going a step further, often times little work has been done on the taxa after the initial publication. This was far worse decades ago and has gotten better since, but various examples can be found still today (e.g. Atrociraptor) with little work done on the taxa themselves and more work done regarding their inclusion in cladograms.

Depiction of some of the largest known hadrosaurs and, therefore, some of the largest known ornithischians, with a adult male for scale

Depiction of Fruitadens haagarorum, with a portion of an adult male for scale

References:

Butler RJ, Galton PM, Porro LB, Chiappe LM, Henderson DM, Erickson GM (2010) Lower limits of ornithischian dinosaur body size inferred from a diminutive new Upper Jurassic heterodontosaurid from North America. Proceedings of the Royal Society B 277: 375–381.

Butler RJ, Porro LB, Galton PM, Chiappe LM (2012) Anatomy and cranial functional morphology of the small-bodied dinosaur Fruitadens haagarorum from the Upper Jurassic of the USA. PLoS ONE 7(4): e31556. doi:10.1371/journal.pone.0031556

Miracinonyx: American cheetah or something else.....

This will be a somewhat short post on a subject that has intrigued me for quite awhile. Not that long ago, geologically speaking, North America was home to numerous felids (cats). While ones that many people know of were present, such as Lynx (bobcat and lynx), Puma (mountain lion) and Panthera onca (jaguar), several others were present that are no longer around. These include, among others, Smilodon (saber-toothed cat), Panthera atrox (American lion), and Miracinonyx (American cheetah). Here, we fill focus briefly on the final one listed, Miracinonyx.

The Carnivores of Rancho La Brea.
From left to right. The dire wolf (Canis dirus), the sabre-toothed cat (Smilodon fatalis), the short-faced bear (Arctodus simus), the cheetah-like cat (Miracinonyx sp.), and the American lion (Panthera atrox). Modified from Turner, A., and Anton, M., The Big Cats and Their Fossil Relatives. Columbia University Press: New York, 1997.

Miracinonyx, commonly called the American cheetah by some, has been found various places throughout North America. Cope (1895) named Uncia inexpectata from some isolated teeth from a cave in Pennsylvania. A second species was named "Felis" studeri from Texas by Savage (1960). Both these would eventually be referred to the genus Miracinonyx (aka American cheetah). Both these taxa were alive pre-Rancholabrean (>240,000 ybp), and Kurten (1976) synonymized both felids with the idea that there was only one Miracinonyx species before the Rancholabrean. Not long after the erection of studeri, Orr (1969) named "F." trumani baed on a skull from a cave in Nevada.

Adams (1979) grouped these taxa together within Acinonyx, the genus of the modern cheetah, due to morphological similarities. He went a step further, however, and grouped them in the subgenus Miracinonyx. The taxonomy of these cats was in a state of flux for awhile, with numerous workers considering the only valid genera to be A. studeri and A. trumani. Van Valkenburgh et al. (1990), however, reported on a remarkable specimen from Hamilton Cave in West Virginia, and concluded that, while A. trumani was valid, it was A. inexpectatus that was the second valid species, with A. studeri as its junior subjective synonym.They also elevated Miracinonyx to the generic level. Van Valkenburgh et al. (1990) were also keen to call them American "cheetah-like cats" rather than American "cheetahs".

Osteological reconstruction of Miracinonyx inexpectatus based on material from Hamilton Cave, West Virginia. Scale = approximately 240 cm (from Van Valkenburgh et al., 1990).

Miracinonyx inexpectatus is the species that first came to be viewed as the "American cheetah". In many ways, the cranial and post-cranial morphology were quite reminiscent of cheetahs today. They have been also, however, commonly compared to Puma, and many researchers have debated which they are more closely related to. While M. inexpectatus had longer and somewhat gracile limbs, M. trumani was, in comparison, a smaller and relatively more robust cat. 

Phylogenetic relationships of the Miracinonyx-Acinonyx lineage based on 27 morphological characters with Leopardus pardalis as the outgroup (from Christiansen and Mazak (2009)).

Miracinonyx has been considered more of a plains species, commonly using Acinonyx (cheetah) as a modern analogue. This is true for both species, even though M. trumani is less similar to Acinonyx than M. inexpectatus, and seems to be more similar morphologically to Puma. This was discussed not long ago by J.P. Hodnett. Hodnett, in an upcoming study, discusses remains of M. trumani from caves in the Grand Canyon of Arizona. Rather than living in a plains habitat, it seemed to be living in a more mountainous terrain with lots of elevation change. 

Adult Snow Leopard (Uncia uncia)

Hodnett took it a step further though, and compared Miracinonyx trumani to the ultimate modern felid adventurer, Uncia uncia, or the snow leopard. He felt that, in order to be agile and a top predator in the Grand Canyon, that M. trumani would have been behaving similar to the snow leopard. 

So, Miracinonyx similar to the snow leopard? It seems like a bit too extreme. Puma behaves, in some ways, similar to Uncia, although in many ways the former is more of a habitat generalist, doing well in a wide variety of habitats throughout North America. Acinonyx, on the other hand, is specialized for open habitat, and Uncia tends to stick to mountainous areas.

With that being said, is Miracinonyx still the American cheetah? Is it the "American Puma"/ancient ancestor of the modern Puma? Or could it be the American snow leopard? While I would lean towards it being more of a generalist like the puma, it could also turn out that M. inexpectatus behaved like the cheetah, while M. trumani behaved like the mountain lion, so one answer will not suffice. Presumably, time and further research will tell us the answer.

References:

 

Adams, D.B. 1979. The cheetah: native American. Science 205:1155-1158.

Christiansen, P. and Mazák, J.H. 2009. A primitive Late Pliocene cheetah, and evolution of the cheetah lineage. Proceedings of the National Academy of Sciences 106(2):512-515.

Cope, E.D. 1895. The fossil vertebrates from the fissure at Port Kennedy Cave, Pennsylvania. Proceedings, Academy of Natural Sciences, Philadelphia 1895:446-451.

Hodnett, J-P., White, R.S., Carpenter, M., and Mead, J.I. in prep. Miracinonyx trumani (Carnivora: Felidae) from the Rancholabrean of the Grand Canyon, Arizona and its implications on the ecology of the “American cheetah”.

Kurtén, B. 1976. Fossil puma (Mammalia: Felidae) in North America. Netherlands Journal of Zoology 26:502-534.

Orr, P.C. 1969. Felis trumani a new radiocarbon dated cat skull from Crypt Cave, Nevada. Bulletin of the Santa Barbara Museum of Natural History Department of Geology 2:1-8.

Savage, D.E. 1960. A survey of various late Cenozoic vertebrate faunas of the panhandle of Texas. Part III, Felidae. University of California Publications in Geological Sciences 36:317-343.

Turner, A. and Anton, M. 1997. The Big Cats and Their Fossil Relatives. Columbia University Press, New York. 234 pp.

Van Valkenburgh, B. Grady, F. and Kurtén, B. 1990. The Plio-Pleistocene cheetah-like cat Miracinonyx inexpectatus of North America. Journal of Vertebrate Paleontology 10(4):434-454.

 

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