Tuesday, February 6, 2018

Tracking Cretaceous Birds in South Korea: Gajin-ri Site

Hello, Dear Readers! I'm back! Well, sort of back. I have been down and out with that nasty flu that is going around. It's a bad one. Friends, if you happen to catch it, please please please take the time to get the rest you need to recover. I've taken the time off that I need, and darn if I don't feel the least bit guilty about it.

We last left our intrepid ichnology adventurers enjoying a lunch of mul-naengmyeon. Here our party split up. Martin went back to Dr. Kim Kyung-soo's lab at Chinju University with Sujin to continue collecting data, making latex peels, and tracings of track slabs on to plastic sheets. Rich and I accompanied Dr. Kim to the Fossil Heritage Hall of the Gyeongsangnam-do Institute of Science Education. We were here to see the famous Early Cretaceous Gajin-ri track site. This site was written up scientifically by Kim Jeong-yul and coauthors in 2012 (Dr. Kim Kyung-soo was one of the authors), and it is famous for two main reasons. One, there are SO MANY BIRD TRACKS, with an estimated 600 bird tracks per square meter!
Figure 3 from Kim et al. (2012). Each one of those marks is an individual bird footprint. This is glorious.
Second, the Gajin-ri site is where Ignotornis gajinensis was found! This is a bird track type has the classic Ignotornis look - three forward-pointing toes with webbing in-between them, one long reversed toe (hallux) - but it also has bill scrape marks!
Tracks of Ignotornis gajinensis, with the bill scrape marks. I like to call them swooshes!
These bill scrape marks are very close in shape to those of modern-day spoonbills. Spoonbills get their name from their spoon-shaped bill, which they use to search for food by swooshing their bills through the water and the underwater sediment, stirring up fish and invertebrates.

I love this image of a Eurasian Spoonbill for two reasons: a great view of the bill, and its showing off its foot.
This site is one of many sites in the Republic of Korea that has been designated a Natural Monument (No. 395), but an entire center was built over the site to offer top-notch science outreach and education. I need to show you how wonderful this center is: this is what I dream of happening in northeastern British Columbia.

First, here's entrance sign. Do you see the bird tracks on the sign?
There are three different bird track types on this sign, including the iconic Ignotornis gajinensis and the bill swooshes!
 Once we were in the Center, we immediately saw a sign for Ignotornis gajinensis!

We were eager to see the track surface, which the Center set up so that visitors can walk around the entire exposed surface at an upper and a lower level.

The lower level allows visitors to get up close and personal with the track surface.
There are several track types on this surface, displaying a whole track ecosystem from the Early Cretaceous Period. Here is one of the sauropod trackways.
Sauropod trackway walking towards me.
Small (left) and large (right) sauropod trackways.
You'll notice how dark the pictures are. It seems counter-intuitive that a dark room is the best way to see dinosaur and bird footprints, but it really is. Bright, direct lights wash out all of the details, while a dark room with a low angle light shining over the surface makes the details pop.

Here is the trackway of a small non-avian theropod, walking among the trackways of sauropods and birds.
Birds, theropods, and sauropods, oh my!
If you look at the upper left-hand corner of the above picture, you'll see my shoes. We got to crawl all over the track surface, but I sure as heck wasn't going to drag my rough shoes - with abrasive grit and dirt stuck in the treads - over a fine-grained track surface. It was socks for us!

Since some of the tracks on the middle part of the surface are hard to see, a series of cameras that project a close-up image of the Ignotornis gajinensis tracks on a huge projection screen. It also shows a projection of anyone working on the tracks, putting research on display. In this case, people got to see our socked feet.
The socked foot of Dr. Richard McCrea next to the trackway (and bill swooshes!) of Ignotornis gajinensis. Dr. Kim and I had a bit of a chuckle over this picture.
Not only was there was a track surface live cam, there was a gorgeous mural depicting the Early Cretaceous paleoenvironment, showing the shoreline of the lake complete with sauropods and flocks of birds!
Spoonbill and sandpiper-like birds fly over the future Gajin-ri track site 117 million years ago.
I didn't want to see Ignotornis gajinensis just because it is a famous bird track type: I have research reasons for wanting to see the real deal. I had an idea that I wanted to test: if we didn't have the glorious bill swoops, would we be able to tell Ignotornis gajinenesis apart from Ignotornis mcconnelli? Before visiting this site and seeing the tracks firsthand, I had to rely on measurements and photographs from publications. Now, data and pictures are good, but there's a lot of information that gets washed out in two-dimensional photos. It didn't take me long to abandon the idea that Ignotornis gajinensis and Ignotornis mcconnelli were the same track shape: there are just too many small differences that separate them.

The untrained eye might think I'm pointing out sauropod tracks, but we all know I'm pointing out a really long bird trackway!
We also saw lots of tracks of a track type called Koreanaornis. These are small, three-toed tracks that sometimes - but not all the time - have a small reversed digit impression. These tracks show many individuals skittering all over a wet sandy surface, much like we would see sandpipers at the beach doing today.
A flock of Koreanaornis track makers, likely running all over the lakeshore, looking for food.
We also saw the other fossil interpretive displays. My favorite one (of course) was the interpretive display for Ignotornis gajinensis. This is a good time to point out another similarity between the work our colleagues in South Korea and the work we do in the Peace Region: the scientists design the interpretive displays! Dr. Kim designed this awesome display.
Scientists like Dr. Kim Kyung-soo make awesome science interpretive displays.
Scientists are great at communicating their science to the public.
Check out those awesome spoonbills!
From left to right: Drs. Kim Kyung-soo, Lisa Buckley (me), and Richard McCrea. 
After taking many pictures, and many photogrammetry pictures, and seeing many, many specimens, we drove back to Chinju University to pick up Martin for dinner. Of course, I had to take pictures of these lovely shed exoskeletons of cicadas attached to a quince tree.


We went to a restaurant that only serves two dishes: two variations of stewed ribs. Let me tell you: when a restaurant focuses on one specialty, they do it up right. These ribs were delicious!
I cannot begin to describe the mouth-watering aroma that came from this dish. I have not had better ribs.
That was the end of a very busy day! The next day (September 15) we were scheduled to visit the field sites and collections of the Goseong Dinosaur Museum! Stay tuned!

References

Kim JY, Lockley MG, Seo SJ, Kim KS, Kim SH, Baek KS. 2012.  A paradise of Mesozoic birds: the world's richest and most diverse Cretaceous bird track assemblage from the Early Cretaceous Haman Formation of the Gajin Tracksite, Jinju, Korea. Ichnos 19(1-2): 28-42.

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