Figurative illustration of the new phylogeny by Baron et al. 2017
Most folks who visit my site by now have seen the big dinosaur news that has hit the interwebs. A new study from Matthew Baron, David Norman and Paul Barrett from University of Cambridge and the Natural History Museum of London, has seriously challenged the classic interpretation of dinosaur phylogeny.
Although originally thought of as two unrelated branches of Reptilia that grew to immense size during the Mesozoic (e.g., Charig et al. 1965), for the last 43 years the group, Dinosauria, has been considered monophyletic (i.e., sharing a single origin) with the subgroups, Saurischia & Ornithischia, forming the first major branches within the group (Bakker et al. 1974). Saurischians, or “reptile hips” were aligned together by their similar hip shapes, skull characters (e.g., open antorbital fenestrae), and inferred soft tissues (e.g., air sacs). Ornithischians, or “bird hips” shared a hip structure that was superficially similar to that of birds, with a pubis that pointed caudally rather than rostrally, along with a variety of unique skull characters such as a neomorphic bone known as the predentary.
Study after study showed that this relationship was sound, and so it stayed that way. The problem with getting the same answer over and over again is that one eventually stops questioning it. Consistent results become common knowledge, and may even graduate to dogma. That’s not so bad if that common knowledge is true, but all too often many of these “obvious” cases wind up being just so stories upon closer inspection.
In this day and age there are no shortage of books, websites, and videos dedicated to debunking classic paleo myths. The majority of this mythbusting focuses on myths about dinosaurs. As the poster children for paleontology, this isn’t that surprising. With so many takes on this subject it comes as no surprise that all of the classic dinosaur myths have long since been debunked, such as dinosaurs as low-energy tail draggers, walking around like Godzilla, being evolutionary failures, inferiority to mammals, being pee brained monsters, etc.
However, as quickly as these classic dinosaur myths have been eradicated, new ones have come and taken their place. These myths/misconceptions are routinely cited today without any question despite being just as erroneous as the myths that preceded them.
This is the start of a new series I want to cover on the site: dispelling modern myths in vertebrate paleontology. Given the bent of my website, these myths/misconceptions will largely stay focused on reptile-related animals, though I am open to taking the occasional foray into other animal groups if the myths are egregious enough (which is to say that suggestions are welcomed).
The seminal installment for this series is one that I see mentioned time and again:
Megalochelys atlas skeleton on display at the AMNH. Photo by Clair Houck (Wikipedia)
Today, the largest turtle alive is easily the leatherback turtle (Dermochelys coriacea), at a whopping 916 kg (2,015 lbs, Eckert & Luginbuhl 1988). On land, the largest turtle goes to Chelonoidis nigra (Galápagos tortoise) which has been reliably recorded as reaching up to 417 kg (919 lbs) in weight (Guinness World Records). However, both extant turtles are dwarfed in size by an immense land tortoise that lived as little as 1.7 million years ago, in the Pleistocene.
In another example of slow-cooked science, this paper was the culmination of over three years worth of work collecting data on tegus. For the study, the authors looked at adult black and white tegus (Salvatore merianae). Tegus are an interesting group of lizards. They are the largest members of the family Teiidae and are often referred to as the monitor lizards of the new world, due to their convergent lifestyles (highly predaceous, active foragers). Besides their varanid-like demeanor, tegus are also known for their enormous jowls, especially in the males. The jowls hold the pterygoideus muscles, the big jaw snappers, which have been shown to increase in size for males during the breeding season (Naretto et al. 2014). As reptiles, tegus have been assumed to follow the standard ectothermic lifestyle of requiring external sources of heat to warm their bodies and maintain stable body temperatures. Looking at the natural history of the animals, tegus appear to fit the mold pretty well. They have distinctive winter and summer activity levels. In the summer, the animals regularly maintained body temperatures of 32–35°C, and in the winter they let their body temperatures drop to the temperature of their burrows (15–20°C). This is all fine and good for a bradymetabolic, ectothermic lizard, but when the researchers tracked body temperatures over time they discovered something completely unexpected.
I figured if I was going to do a Jurassic World-related post on Stegosaurus I might as well follow it up with a review for the film. I grossly underestimated the draw of dinosaurs to the cinema. Despite 22 years of Jurassic Park, Walking with Dinosaurs (BBC version, not the Disney thing), and so on, people never seem to be burnt out on dinosaurs. That’s good news for paleontology (yay!), and also for movies seeing as how Jurassic World just raked in a record-breaking $208.8 million domestic in its opening weekend.
So what did I think? In short: I liked it and found it to be a worthy successor to the franchise.
As I write this the US premiere of Jurassic World is just around the corner. I had gone back and forth regarding this post given that we currently know very little about the film and as such the interpretations written about here and elsewhere may well be pointless by the time the film premieres.
Ultimately I decided to post this anyway since the overall thrust of the article should remain true regardless of how the film pans out.
Now there has been a lot of buzz around Jurassic World since it was first announced last year. The buzz has been mixed, but fairly positive. I suspect this was, in part, because everyone was happy to hear that the godawful military dinosaur idea was shelved in favour of a more “traditional” JP franchise storyline. Nonetheless the movie has still drawn its fair share of detractors, including myself. Most of the people who are unhappy with the film are either paleontologists, or hardcore dinophiles. Many of the problems leveled at the film have to do with the portrayal of the extinct animals. The problems are actually myriad ranging from pterosaurs capable of picking up humans using grasping feet, mosasaurs that are twice the size of blue whales, sauropods covered in elephant skin rather than scales (a problem not unique to Jurassic World), everything about Velociraptor, and of course Indominus rex. My biggest beef with the film is that the dinosaurs are not being shown as dinosaurs so much as monsters. However, after The Lost World: Jurassic Park came out it became pretty evident that Spielberg’s original vision of portraying dinosaurs as animals had been shelved in favour of the more entertainment-friendly movie monster approach. However, for what seems like a majority of the detractors, the biggest gripe with the film has to do with a lack of feathers on pretty much all the dinosaurs. This seems to be a common theme these days with a particularly vocal group of dinophiles and paleontologists strongly pushing for the feathering of every dinosaur in sight and insisting that all media that portrays scaly (erroneously called: “naked”) dinosaurs is inaccurate. Never mind the fact that a feathered, pack-hunting, 2 meter tall Velociraptor mongoliensis is still every bit as inaccurate as a scaly one.
Anyway, I digress. Dealing with the overwhelming amount of internet drama surrounding Jurassic World (and the media depiction of dinosaurs in general) is a topic for another day. My reason for writing this post is centered around one particular criticism that popped up a few weeks ago.
Visitors to the site may have noticed that it has been stuck in archive mode for the past however many months. This only recently came to my attention when I had noticed a lack of update nags from WordPress. Further investigation revealed that comments were no longer going through, nor were new posts. Given the global lockdown of the site I suspected that I was either hacked (again!) or that there was a database issue. A quick scan from Sucuri eliminated the first option (or at least made it less likely), which led me to check the database.
Lo and behold I found that the Reptipage database is currently holding at approximately 150 MB. Unfortunately, my current webhost (1and1.com) had a hard limit of 100 MB for databases at my current hosting level. I say “had” because they have since bumped database sizes up to 1GB. The problem was that any old databases currently in use were still subjected to this hard limit. I was 50MB over the hard limit so the MYSQL database was locked down. Hence the lack of updates, comments, posts, etc. I would have caught this sooner, but the demands of my current job have caused the site to get backburnered.
The site is now on a new database that has more legroom to it and I’m now aware of this looming problem (the DB isn’t 1GB now, but it will be in the future). I’m looking into spreading the Reptipage across a few databases using the hyperDB plugin. We’ll see where it goes.
Also, there has been a bit of a lull in my current workflow that has freed up some time that I intend to devote to writing again. Between T. rex autopsy and Jurassic World (both coming out in a few weeks) there is no shortage of excitement, controversy and overall butthurt on the internet that I can talk about. There has also been a bevy of cool new things regarding extant reptiles which I intend to get back to covering.
So that is the current status of things. I have some posts in the hopper that should be coming out shortly. I apologize for having the site in archive mode for so long.
I finally got around to making the site more social-media friendly. You should now have the ability to easily share posts on all the major social media services.
I also fixed a bug in the CSS that kept the font colour for the author fill-in fields black. My apologies to everyone who has been commenting in spite of the problem. I was not aware of it until recently. I also wasn’t aware that you could not subscribe to comments, so I fixed that problem too. You can now subscribe to posts with or without commenting. You can also receive notifications for just replies to your comments if that is what you prefer.
Hopefully the site is a bit more user friendly now. Let me know if anything else is broken.
[Update: I also updated the theme from (which I had not changed since 2007). The old theme would not allow for threaded commenting, which can be extremely frustrating when there are extensive comments. The new theme allows for this and a host of other things too. Now I just need to fix about a dozen small little bugs and things should be good.]
Artist’s impression of the fleshed out Kulinda specimen. Image by Andrey Atuchin
Well, as is often the case, this post is a bit late to the party, despite starting early. Unless you have been living under a rock (or don’t care that much about dinosaurs), you have probably heard about the discovery of a small ornithischian from Siberia, Russia that apparently sports feathers as well as scales on its body. It’s a crazy half-and-half animal that has given many the green light for making all dinosaurs feathery.
As is often the case with these studies I am writing to urge caution against taking things too far, if just so there is some voice of dissent out there in an internet fully of trigger-happy feather reconstructions.
One of the quintessential depictions of prehistoric times is that of an ancient, often volcano ridden, landscape full of animals bearing large showy sails of skin stretched over their backs. Sailbacked animals are rather rare in our modern day and age, but back in the Mesozoic and Paleozoic there were sails a plenty.
By far the most popular sailbacked taxa of all time would be the pelycosaurs in the genus Dimetrodon. These were some of the largest predators of the Permian (up to 4.6 meters [15 feet] long in the largest species). Dimetrodon lived alongside other sailbacked pelycosaurs including the genus Edaphosaurus. These were large herbivores (~3.5 m [11.5 ft] in length) that evolved their sails independently from Dimetrodon. The Permian saw many species of sphenacodontids and edaphosaurids, many of which sported these showy sails (Fig. 1. [1–8]).
However sails were hardly a pelycosaur novelty. The contemporaneous temnospondyl Platyhystrix rugosus (Fig. 1 [9]) also adorned a showy sail.
Fast forward 47 million years into the Triassic and we find the rauisuchians Arizonasaurus babbitti,Lotosaurus adentus, Xilousuchus sapingensis, and Ctenosauriscuskoeneni , all bearing showing sails on their backs (Fig. 1 [10–13]). Much like in the Permian, many of these taxa were contemporaneous and, while related, many likely evolved their sails separately from one another.
There are currently no fossils of sailbacked tetrapods in the Jurassic (as far as I know. Feel free to chime in in the comments if you know of some examples). However the Early Cretaceous gave us a preponderance of sailbacked dinosaurs (Fig. 1 [14–19]) including the cinematically famous theropod Spinosaurus aegyptiacus, the contemporaneous hadrosaur Ouranosaurus nigeriensis, the gharial-mimic Suchomimus tenerensis, the potentially dual sailed sauropod Amargasaurus cazaui, as well as the allosauroids Acrocanthosaurusatokensis, and Concavenator corcovatus. Lastly, the discovery announced last year (and just now coming to light in the news) of better remains for the giant ornithomimid Deinocheirusmirificus have revealed that it too may have sported a small sail along its back.
Once again we find a group of related, largely contemporaneous, animals, most of which probably evolved their sails separately.
Such a huge collection of sailbacked animals all living around the same time (and sometimes the same place) has begged for some type of functional explanation. The usual go-to for large, showy surfaces like these or the plates of Stegosaurus has been thermoregulation. The thinking being that blood pumped through a large surface area like this, when exposed to the sun, has the ability to warm up faster than other areas of the body. Conversely when the sail is placed crosswise to a wind stream, or parallel to the orientation of the sun, heat will radiate out into the environment faster than other areas of the body. That most sailbacked dinosaurs were “localized” to equatorial areas, coupled with the large sizes of all the taxa (1-10 tonnes depending in species) has favoured a cooling mechanism function for dinosaur sails. Whereas a heating function has been presumed to be the primary function for sails in Dimetrodon and Edaphosaurus. No real function has been ascribed to the sails in rauisuchians or Platyhystrix, though this is probably due to a lack of knowledge/interest in these groups.
Alternate functions proposed for these sails have included a self-righting mechanism for swimming, sexual signaling and other presumed display functions. In certain cases, namely Spinosaurus aegyptiacus and Ouranosaurus nigeriensis, it has even been argued that the enlarged spines did not support a sail, but rather were supports for a large, fatty hump akin to that of camels or bison (Bailey 1996, 1997).
Given the wealth of hypotheses for potential sail functions it would be beneficial to first understand what extant sailbacked taxa use their sails for. Unfortunately—though unsurprisingly—there are few if any scientific studies on sail use in extant sailbacked animals. This has lead to the apparent assumption that there are no extant vertebrates with sailbacks.
There are, in fact, quite a few sailbacked animals alive today. These include various fish, amphibians and even reptile species. Learning what these taxa use their sails for may offer us a glimpse at what extinct animals were doing with their sails. Continue reading → Post ID 1652
