Hell Creek Formation

* Hell Creek Formation
* Lance Formation
* Scollard Formation

### Filmed In

**Hell Creek Formation*** Bog Pond, Waterford, Oxford County, Maine, USA (Swamps, Segment 5)

**Lance Formation**

* Winterfold Forest, western Greensand Ridge, Surrey, England (North America, Segment 5)

**Scollard Formation**

* Lake Morena County Park, San Diego, California, USA (Swamps, Segment 4)

## Characteristics

### Environment

Coastal, Estuarine, Floodplain, Fluvial, Forest, Lacustrine, Swamp

### Notable Areas

Tanis Fossil Site

The ***Hell Creek Formation***, named for exposures studied along Hell Creek, by Jordan, Montana, is a formation that stretches across parts of Montana, North and South Dakota, and Wyoming. It is one of the most known and most heavily-studied Late Cretaceous formations of North America.

Along with the ***Lance Formation*** (named after Lance Creek, Wyoming) and the ***Scollard Formation*** of southwest Alberta, Canada, Hell Creek forms a section of the eastern shores of Laramidia, serving as one of the western coasts of the inland sea that splits North America in half.

## Description

During the Maastrichtian stage of the Late Cretaceous Period, Hell Creek was full of estuaries, floodplains, forests, lakes, rivers, swampy lowlands, and coastal plains, kept constantly humid by ample rainfall and a subtropical climate warmer than the region today (hence, there was no cold season in those areas back then).

These conditions climate helped support conifers, ferns, flowering plants, palmettos, and ferns in swamps, as well as ash trees, conifers, canopy and understory plants, oaks, and shrubs in forests. The area by northwestern South Dakota is a coal-rich wetland environment fit for supporting angiosperms, but also (to a lesser degree) conifers, cycads, cypresses, and ferns. Several sites also preserve fossilized leaves that indicate a forest of small trees

One area of Hell Creek, known as the "Tanis Fossil Site", is believed to preserve a catastrophic moment that occurred 66.043 million years ago, in the wake of the Chixiclub asteroid impact that wiped three quarters of all life on Earth, including all non-avian dinosaurs. Preserved traces of the disaster include millions of mikrotektites (molten debris generated by the asteroid impact) that weren't reworked into different layers, a turtle impaled on a tree branch, large primitive feathers, compacted plants, fish that suffocated during the impact, with their skeletons indicating that the impact occured during spring, drowned ants, eggs and hatchlings, and broken remains of almost all known dinosaur groups in the Hell Creek Formation, among them the partially-mummified foot of a *Thescelosaurus* with the skin still intact.

While rich in dinosaurs and other terrestrial creatures, surprisingly, a mosasaurine measuring at least 11 meters (36 feet) long was found in the area. It is possible that this animal is a sub-adult form of *Mosasaurus* itself, given its status as a cosmopolitan species (being found on all seven continents). It is likely that this is meant to be the animal portrayed going after the *T. rex* family in Coasts, explaining why it is identical to the fifty-foot "Hoffmann's Mosasaur" found in the fourth segment of Coasts and the fourth segment of Oceans. Azhdarchid vertebrae has also been found in the Hell Creek Formation, indicating that *Quetzalcoatlus* or a similar animal lived in the area.

## Appearances

***“ Across this vast continent, there are over a hundred thousand square miles of swamplands. And most of them remain flooded all year-round. ”***

― **David Attenborough**, *Swamps*
The Hell Creek Formation is the setting of the fifth segment of Swamps, which shows a pair of *T. rexes* ambushing an *Edmontosaurus* at night. It also appears to be the likely setting of the first segment of Coasts, where a *T. rex* leads his hatchlings to an offshore island. It may possibly be the setting of the second segment of Freshwater, though it's also possible that this is set in the neighboring Lance Formation.

***“ Further north, the Rocky Mountains are still slowly rising. And as they do, they create higher, cooler landscapes where vast pine forests flourish. ”***

― **David Attenborough**, *North America*
The Lance Formation is the setting of the fourth segment of North America, where male *Triceratops* show off and fight rivals to impress females during the mating season. It might also be the likely setting of the second segment of Freshwater and the second segment of Forests, both of which show thick forests inhabited by *Triceratops*, one of which got hunted down by a *T. rex* in Freshwater.

***“ A devil toad can only survive here because every year, the land is flooded by seasonal rains. However, there are places where changing climate means the rains are less-certain. This inland basin in North America was, in the past, several feet deep in water. But after a decade of drought, it's now bone-dry. Nonetheless, some dinosaurs still linger here. ”***

― **David Attenborough**, *Swamps*
The Scollard Formation is the setting of the fourth segment of Swamps, which depicts an inland basin that used to be several feet deep in water, dried up by a decade-long drought, where an old *Pachycephalosaurus* defends his leadership over the herd against a young challenger.

## Fauna

*Edmontosaurus annectens**Mosasaurus hoffmannii**Pachycephalosaurus wyomingensis**Pectinodon bakkeri*Protostegid"Styginetta longfreni"*Triceratops horridus**Tyrannosaurus rex*The non-avian dinosaurs of the Hell Creek, Lance, and Scollard Formations
## References

1. ↑ 1.0 1.1 1.2 1.3 I Know Dino: The Big Dinosaur Podcast, Episode 445: Dinosaurs in Swamps: Featuring Prehistoric Planet 2
2. ↑ 2.0 2.1 I Know Dino: The Big Dinosaur Podcast, Episode 447: Dinosaurs in North America: Featuring Prehistoric Planet 2
3. ↑ Dinosaur extinction battle flares
4. ↑ Asteroid impact in vivid detail
5. ↑ A Turtle from the Tanis KPG Mass-death Assemblage: Further Evidence for Circum-riparian Disruption by a Massive Chicxulub Impact-triggered Surge
6. ↑ The Mesozoic terminated in boreal spring
7. ↑ A Blast from the Past: Geochemical Identity of the Chicxulub Bolide and Immediate Effects of the Impact, recorded at Tanis, North Dakota
8. ↑ The first in situ collection of a mosasaurine from the marine Breien Member of the Hell Creek Formation in south-central North Dakota, USA