W3 MAIN

The W3 Main tracksite is found about 3km to the northwest of E2-Pit on the same anticline (the Two Camp Anticline). This tracksite shows a diversity of in situ tracks and trackways on a scale rarely seen worldwide. Over 10,000 footprints occur on a footwall exceeding 60 metres in height at an angle of 60 degrees.

Wide angle of a portion of the W3 Main tracksite (2002)

 

The only way to get at the tracks at the W3 site is by the use of ropes.

Mr. Mark Mitchell (Technician - Royal Tyrrell Museum of Palaeontology) making latex peels of some of the tracks in August, 1998.

(Click on picture to see mapped area from 1998 research)

 Darren Tanke (Technician - Royal Tyrrell Museum of Palaeontology) was one of the first researchers to be on the W3 Main footwall. He described the uncomfortable feeling associated with having rocks that had become dislodged from up top whizzing past his head (Darren Tanke, pers. comm.).

The W3 site has the highest diversity of tracks out of all the sites exposed in the area to date. As a part of the research on this site an area of 500m2 area (approximately 1/12 of the total area of the W3 Main tracksite) was mapped.

There are the big (up to 50 cm in length) tridactyl tracks and trackways of large theropods (Irenesauripus mclearni) which are the most prominent when viewing this site, excepting perhaps for the ankylosaur tracks. These large meat-eating dinosaurs covered 3 metres with a single stride at a walk. Initial estimates of the height of the W3 Main footwall were made by by counting the number of strides in one I. mclearni trackway. The large theropods make up a very small percentage of the total number of tracks and trackways in the 500m2 study area (1.5% and 4.2% respectively).

   

Large theropod trackway (left) and footprint (right) from the W3 Main tracksite

There are at least two types of "medium-sized" (between 18-27cm in length) theropod tracks and trackways at this site which account for a significant portion of the vertebrate ichnofauna at this site (19% and 51% respectively). The strides of these medium-sized theropods are generally around 2 metres at a walk, but some do pick up the pace somewhat with strides nearing 3 metres length. One of these track types is Columbosauripus ichnosp. an ichnotaxon originally described from the Peace River Canyon though the Grande Cache variety is over twice the size of those from the Gething Formation.


Columbosauripus ichnosp. print from the W3 Main tracksite

 

Another footprint type, Gypsichnites pascensis, is also present at the W3 site. G. pascensis tracks were originally attributed to plant-eating ornithopod dinosaurs, due to the blunt, hoof-like nature of the toes. Many of the G. pascensis tracks and trackways appear this way, however it has been observed that within a trackway of typical G. pascensis tracks several prints were found to have a decidedly theropod aspect , including some with distinct claw impressions.

   

Typical form of Gypsichnites pascensis print from W3 footwall (left) and a drawing of a

more theropod-like form from the same trackway (right)

The smallest non-avian dinosaur tracks (Irenichnites gracilis) are also those of theropods, and have average footprint lengths around 15 cm. These small dinosaurs also made up a small percentage of the footprint fauna of the 500m2 study area (1.6% and 4% respectively). Stride lengths of 1.5 metres were of a normal walk, but one trackway was measured with stride lengths in excess of 2.5 metres! Quite a lot of ground to cover for such small feet.

Drawing of an Irenichnites track from the W3 Main footwall.

Of course there are ankylosaur tracks, since they are found at all tracksites in the Smoky River Coal Mine. Though they were not the dominant track type at the W3 Main site, ankylosaur tracks and trackways still made up a respectable proportion of the vertebrate ichnofauna (17% and 15% respectively). The ankylosaurs had large footprints (between 40-50 cm long) with a width only slightly less than length. Their handprints were about 2/3 the area of footprints. Within the mine ankylosaur tracks number in the several thousands, but the preservation is often less than pristine (a close to two ton animal disturbs the ground a great deal tending to obliterate most of the finer details of the footprint. The strides of these animals average out to about 1.5 metres. They did not appear to be in too much of a hurry.

A footprint (lower) and handprint (upper) set from an ankylosaur trackway (Tetrapodosaurus borealis) at the W3 Main site

 

The non-dinosaurian component of the W3 Main site are represented by the footprints and trackways of what must have been fairly large birds (Aquatilavipes curriei), with an average footprint length 9cm. In fact the avian footprints dominate the W3 local ichnofauna with a whopping 60% of the total number of footprints and 29% of the trackways! The W3 Main birds have an average stride of 0.5 metres. This is too much ground for short-legged birds to cover and so were likely long-legged wading birds, something similar in design to a heron or crane perhaps. There is no indication of a hallux (dew claw) impression associated with these prints and they are functionally tridactyl.

                          

Map (left) and photograph (right) of bird footprints and trackways (Aquatilavipes curriei) from the W3 Main site

 

         

Photograph and drawing of an A. curriei print from W3 Main

All in all the W3 Main site is nothing short of impressive, especially in good light when hundreds of tracks and trackways are visible criss-crossing over the entire face of the footwall. In poor light tracks are nearly invisible. Tracking is very, very light dependent, but even in the best light only 20-30% of the tracks are visible since most of the tracks (those of the birds and small theropods for instance) are too small to see from the ground. Even some of the medium-sized prints can be too faint to see from a distance, but for all that the view is still spectacular!