January 30 , 2017:
by Henry Sharpe
The Peace Region of Alberta and British Columbia has recently been exposed as a haven for palaeontology. However, the vast majority of vertebrate fauna from this region are terrestrial, and very little marine fauna was known. That is, however, until a 2014 paper highlighted the remains from 8 marine reptiles from just north of Grande Prairie.
Sea Monsters from the Peace Region
The Peace Region of Alberta and British Columbia has recently been exposed as a haven for palaeontology(1). Here, not only fossils but trackways have been uncovered, including one famous example that showed a group of Tyrannosaurs on the prowl. However, the vast majority of vertebrate fauna from this region are terrestrial, and very little marine fauna was known(2). That is, however, until a 2014 paper by Phil R. Bell, Frederico Fanti, Mark T. Mitchell and Philip J. Currie (the namesake of the Peace Region’s Philip J. Currie Dinosaur Museum) highlighted the remains from 8 marine reptiles from just north of Grande Prairie(3).
Although the material was two fragmentary to confidently assign to genus level, they were complete enough to assign 5 of them to family levels, and 3 to subfamily levels. According to the paper, the material recovered represented 4 Polycotylids, 2 Plioplatecarpines, 1 Russelosaurine and 1 Elasmosaurid. The paper also mentions additional material from Mosasaurs and Plesiosaurs, as well as the two fish Xiphactinus and Protosphyraena, recorded in an unpublished dissertation. This implies that the oceans near Grande Prairie were just as teeming with life as the seas to the south, with similar marine reptile and fish faunas(3).
The Cretaceous Arctic Circle
The North Pole is not static in location. About 85 million years ago, the arctic circle, which remains at about 66 degrees in latitude, lay right over the Puskwaskau Formation, meaning that these animals existed at a very high latitude in the Cretaceous(3). Despite this, however, the possibility of these animals seeing snow was very small, as the mean global temperature was higher, and freezing temperatures at sea level would have only been possible at latitudes over 80 degrees(4).
This is not saying that there were no freezing temperatures at all at this latitude, as there may have been [not enough work has been done on this topic, although the samples that lead to the conclusion that sub-zero temperatures only ever occurred at higher than 80 degrees were from taxa that lived at low elevations (theropods, large herbivores, crocodilians, fish etc.). Other studies have proposed that at higher elevations freezing temperatures would have occurred at lower latitudes (5)].
This was the first part in a 4-part series documenting these high-latitude Mosasaurs. Next time, I will cover the Mosasaurs of Hornby and Vancouver Island, which was just farther north in latitude than the Puskwaskau Formation.
1 “History of Discovery.” Grande Prairie Regional College. N.p., n.d. Web. 04 Jan. 2017.
2 “Dinosaurs of the Peace Region.” Grande Prairie Regional College. N.p., n.d. Web. 04 Jan. 2017.
3 Bell, Phil R., Federico Fanti, Mark T. Mitchell, and Philip J. Currie. “Marine Reptiles (Plesiosauria and Mosasauridae) from the Puskwaskau Formation (Santonian-Campanian), West-Central Alberta.” Journal of Paleontology 88.1 (2014): 187-94. Web.
4 Amiot, Romain, Christophe Lécuyer, Eric Buffetaut, Frédéric Fluteau, Serge Legendre, and Francois Martineau. “Latitudinal Temperature Gradient during the Cretaceous Upper Campanian-Middle Maastrichtian: δ18O Record of Continental Vertebrates.” Earth and Planetary Science Letters 226.1-2 (2004): 255-72. Web.
5 Spicer, R. A., and J. T. Parrish. “Late Cretaceous-early Tertiary Palaeoclimates of Northern High Latitudes: A Quantitative View.” Journal of the Geological Society 147.2 (1990): 329-41. Web.
6 Blakely, Ron, Ph.D. “Paleogeography and Geologic Evolution of North America.” Northern Arizona University. N.p., n.d. Web. 04 Jan. 2017.