Saurian DevLog #47

 

Hey all,

We've been working really hard on getting the next patch out, as well as the art book so all of the team is in ultra-busy mode at the moment. Henry has some information for you on what is to come with regards to the patch and I thought I'd drop some science seeing as an interesting new paper just dropped that we got a first-look at.

Henry

The programming team has been busy working out the last bugs from the gradual ontogeny system implementation, as well as some other longer-standing ones. After some last-minute sprints, we're happy to say it's ready! Patch notes can be found here - please let us know if you encounter any issues. Otherwise, enjoy!

Tom

A bit ago we were contacted by palaeontologist Mike Lee, asking if they could use our Thoracosaurus render in the press release of a new paper he had in the works featuring this animal. Always happy to have our art used for sci-comm, we said yes and Mike was kind enough to send us a pre-print of the paper in question. It turned out to be a pretty cool study, and had some implications for us which I thought would be interesting to discuss. Seeing as it has now been published I thought I'd talk about it here today.

To be clear, it won't effect how the animal will appear in game, but I did have to re-write the profiles for all our crocodylomorphs in the art book and I will have to modify the encyclopedia entries as well.

  Thoracosaurus  in Saurian.

Thoracosaurus in Saurian.

Thoracosaurus is a genus of large (5m or more) marine crocodylomorph from the late cretaceous of North America (including Hell Creek) and Europe. Since it was first discovered, Thoracosaurus has been considered an early member of the gharial lineage, with many similar aspects of the skeleton indicating this might have been the case. Computational phylogenetic analysis - computer run analysis that hypothesise the relationships of organisms - also consistently came to the same conclusion.

Borealosuchus is another crocodylomorph from Hell Creek that sometimes comes out as close to gharials, and sometimes in other positions close to the base of living crocodilians.

Traditional morphological studies had found gharials to be the earliest branching group of crocodylians. This was consistent with the 72 million year age of the earliest species of Thoracosaurus. However, new relationships and divergent dates received from molecular studies did not, with gharials being a reletively young group (40 Ma) more closely related to crocodiles than alligators. In this scenario, Thoracosaurus appears far before when gharials are supposed to have diverged from crocodiles.

Thoracosaurus tree.png

This is where the new study by Mike Lee and his colleague Adam Yates comes in. They found that when running extremely complete phylogenies taking molecular, morphological and fossil age data into account, this disparity was resolved.

The inclusion of data related to age gaps between groups (tip-dating methodology) proved to be the difference, as without these methods the relationships came out similar to previous studies. The inclusion of tip-dating Bayesian approaches found Thoracosaurus and Borealosuchus to not be related to gharials at all, but outside of crocodylia. The position of gharials here agrees with molecular approaches, being young and close to crocodiles. This means than the gharial-like features of Thoracosaurus are all convergently evolved, probably as adaptions for catching fish.

So what does this mean for us, on a surface level? Well probably not a lot in terms of appearance, behaviour and ecology. What it does mean is than both Thoracosaurus and Borealosuchus are no longer crocodylians! They are stem-crocodylians and each other's closest reletives. So our crocodylian count in Saurian has dropped from 3 to 1, with early alligatoroid Brachychampsa being the only one left.

 
Tom Parker11 Comments