The world can always use some more Pachyrhinosaurus
bonebeds. So hooray to my friends and colleagues Federico Fanti and Mike Burns,
and my PhD supervisor Phil Currie, for publishing a description of the Wapiti River Pachyrhinosaurus bonebed (currently in 'early view' accepted manuscript
form at the Canadian Journal of Earth Sciences).
A friendly Pachyrhinosaurus lakustai greets students at Grande Prairie Regional College!
Most of the time, dinosaur palaeontologists look for bones
in dry, barren landscapes – the badlands of Alberta, the Gobi Desert, etc –
places that have lots of rocks and not much covering them up, like inconvenient
forests or cities. But sometimes, you don't have vast expanses of outcrop. In
Nova Scotia, we dig up dinosaurs on the beach. In the area around Grande
Prairie, Alberta, you look for bones in the outcrops along rivers and streams.
The very first summer I went out with the University of
Alberta crew (way back in the halcyon days of 2007; the first Transformers
movie was 'good', everybody read the last Harry Potter book overnight to avoid
spoilers, and...apparently not much was happening in my musical spheres, but
my, how time has flown), there wasn't a Wapiti River bonebed. We knew that
there were bones coming out of the riverbank somewhere, but it took the better
part of a day to trace them up the hill to the bone layer.
See if you can spot Phil for scale way up on the hill there, and remember that Phil is about 3x as tall as most humans. That's where the bone layer is!
It's a pretty steep
hill, and so those first few days excavating the bone layer meant hacking out
little footholds and gradually making enough of a ledge for us to sit on and
walk around each other without plummeting to our death.
The last time I was there, in 2011, the ledge had expanded
significantly, although you can see it's still a pretty narrow slice! It's a
scenic place to work, with the river and boreal forest stretching away below;
bear sightings were not uncommon (and occassionally closer than we'd all
prefer), and I remember a hummingbird came down to check on us one day, buzzing
around my head for a few moments!
In this bonebed, there's a layer of bones in a crazy,
mixed-up layer of folded mudstones, and those are pretty easy to excavate.
Here's a dorsal vertebra. Nice and easy.
But
down beneath that, the skulls and larger bones are encased within super hard
ironstones. We can't really do much with these in the field, so we need to take
them out in huge pieces.
And here's what the skulls look like. The circular depression down towards my left foot is the narial opening. The UALVP has like 15 of these suckers and they each take about 2 years to prepare with a crack hammer and chisel.
But the bonebed is also about halfway down into the
river valley on a steep slope that's hard enough to just haul yourself up, let
alone a huge boulder. So we've been very lucky to have helicopter support to
carry out some of the heaviest pieces at the end of each field season.
Up, up and away!
Sometimes we were even visited by Aluk the Pachyrhinosaurus,
mascot of the Arctic Winter Games in 2009!
This was probably the strangest day in the field.
There's still much more work to be done on this bonebed – we
still aren't exactly sure what species of Pachyrhinosaurus is present. The age
is right for P. canadensis, but only time will tell. And with two
Pachyrhinosaurus bonebeds in Grande Prairie – the Pipestone Creek bonebed with
P. lakustai, and the slightly younger Wapiti River bonebed – there's bound to
be much more to learn about the evolution and biology of this unusual
ceratopsian.
Wapiti River Fieldwork, Part 1
Wapiti River Fieldwork, Part 2
And don't forget to check out:
Fanti F, Currie PJ, Burns ME. 2015. Taphonomy, age, and paleoecological implication of a new Pachyrhinosaurus (Dinosauria: Ceratopsidae) bonebed from the Upper Cretaceous (Campanian) Wapiti Formation of Alberta, Canada. Canadian Journal of Earth Sciences, early view.
No comments:
Post a Comment