A tough call

Here is another example of how difficult it is to try to interpret a flawed track. Again, it is probably a theropod from the Main Brijun, Pogledalo promontory. If true, the length of the (right pes) print is about 65 cm. The main problem is that many tracks consist of both positive and negative; the concave and convex (in filling) impression. The prominent part (either positive or negative) of the footprint is usually in the distal toes area. Or there's where the deepest part of the impression is situated, if the mud is deep. But quite often it can be a combination: some toe prints have in filling while some don't.  Than there is the displacement rim problem. It can also be negative or positive. The problem of mud collapse, etc...

An excellent paper (pdf file is free to download) on the subject of track identification:

Intra-Trackway Morphological Variations Due to Substrate Consistency: The El Frontal Dinosaur Tracksite (Lower Cretaceous, Spain)

 

Dinosaurs were messy ... (3)

Here is an example how hard it can be to correctly identify the tracks. I have photographed a small fraction of the Barremian (cca 125 mya) dinoturbation at the Pogledalo promontory of the Main Brijun island in Istria (Croatia).
Outlined with the red line are all the visible theropod footprints. A very large single foot impression is only partly visible under the covering sediment. Applying Dalla Vecchia's ideal footprint model of the theropod from that site (the green silhouette) I managed deriving the track size of that particular theropod. It was bout 65 cm long. The beast itself was at least 10-11 meters long. The size of an adult  Altispinax. Other footprints are from considerably smaller individuals. The prints were distorted due to the mud collapse. There are at least 8 theropod footprints in this photo. Probably more.

The largest theropod trackway in the world?

That Summer of 2011, I couldn't believe my own eyes. After finding some really huge single theropod footprints near Pula, measuring about a meter in length, I managed discovering even larger theropod tracks there. What's more, they were in a sequence: 5 large footprints in a row with regular spacing in between and the adequate pace angulation! There were a few of the prints of the same size and shape outside the trackway as well. Alas, all poorly preserved. Some large iguanodontoid footprints were near, too.
Here is a couple of photographs showing the trackway. I have posted two views for better understanding: from the starting point and from the finishing point. Footprints # 2 and #3 were collapsed in deep mud, while #5 is obviously an overtrack. No 4 is relatively best preserved.
Now hold your breath: the size of the footprint is some 115-125 cm in length, dwarfing any other similar find in the whole world! The footprints were rather broad, but they differ from the ornitischian ones by the relatively slender toes.

There is no way we can identify the exact track maker. However, it might have been one from the stock of the largest predatory dinosaurs of the mid-Cretaceous: a carcharodontosaurid or a spinosaurid. Anyhow, the theropod that left these enormous footprints must have been at least 18 meters long. Below is my restoration of the possible Pula environment with some of the possible track makers.

My article on the finds of giant theropod tracks in Pula was published in 2010 in "Vecernji list" (a major Croatian newspaper)  and in "Zivljenje in tehnika" (a major Slovenian popular science magazine) - "Po stopinjah dinozavrov v Istri" 3/62. I have yet to write the paper.

Notice: The fact that this post is dated April the 1st is just a coincidence. The photographs and the data are genuine and serious and have nothing to do with "April the fools' day".

Dinosaurs were messy ... (2)

If you were suspicious of my theropod tracks interpretation from the previous post, here is a photograph from the same outcrop showing a rather poorly preserved (possibly consisting of under prints) theropod trackway of the animal that had the same shape and size of the foot.

The tracks on the right don't have the distinctive features, so I couldn't figure out their makers (yet).

Dinosaurs were messy ...

... when leaving their tracks!

So, you have decided on finding your own dinosaur tracks? The ones nobody has noticed yet? Or at least nobody has  announced his/her finds publicly. You are expecting to find a nice trackway on a relatively flat rocky surface? Possibly three-toed nice and clear theropod footprints in a sequence? Yeah, right! Chances of finding a track like that are almost equal to finding a nicely preserved relatively complete and articulated fossil skeleton. 

Take a look at the muddy paths where humans and animals left their traces today or yesterday. Are these all well defined traces? Come back in a week and see what's left of them. Consider that dinosaurs left their tracks millions of years ago...

Here is my attempt of interpreting some (probable) theropod tracks from Pula, that are about 100 million years old. They were preserved during the low tide.

Tyrannosaurus rex feeding habits

 In case you've mised this here is the recent post from my gag cartoons site Oberon Cartoons
 T.rex and his paleo diet

Here is my new paleo cartoon, not to be confused for a paleo diet. It's dealing strictly with Tyrannosaurus rex feeding habits. If you want the paleo diet recipes, please, go elsewhere.

My old view at the good old T.rex

Here is my quarter of a century old Tyrannosaurus rex painting. If you look at it carefully, you'll notice the "fleshy" lizard-like lips on the beloved theropod. Given an even a closer look at the painting, you'll notice a few water birds in the background. The birds caused sort of a commotion among the visitors, who thought they were educated in the issue, at the opening of the exhibition of my prehistoric animals paintings at the Croatian Natural History Museum in Zagreb in 1994. Most people knew only about the Archaeopteryx as the sole Mesozoic bird at the time, so my intentional provocation with the duck-like birds hit the chord. I know that this sounds like a joke today, but the greatest bird (and dinosaur) discoveries were yet to come.

Also notice the legs are not in a (popular) squatting position, but more errect, which does make sense for the animal of that size.

The painting was produced in gouache in 1988 and it has been in the collection of the CNHM in Zagreb since 1991.