Preserved tracks in Alaska park suggest duck-billed dinosaurs lived in Arctic year-round

Jul 10, 2014 by Bob Yirka report
Figure 3 from Fiorillo et al. A–C: Size ranges of tracks found at Denali National Park, Alaska, tracksite. D: Adult hadrosaurid track with skin impressions. Scale bar for C1 is 5 cm. Credit: Geological Society of America

(Phys.org) —A trio of researchers has published the results of a study of dinosaur tracks found in Alaska's Denali National Park in 2007. Anthony Fiorillo, Stephen Hasiotis and Yoshitsugu Kobayashi, of the Perot Museum, the University of Kansas and Hokkaido Museum respectively, report, in an article published in the journal Geology, on their analysis of 70 million year old hadrosaur footprints and what they revealed about the lifestyle of the dinosaurs.

Hadrosaurs, more commonly referred to as duck-billed (because of their unique crest) lived approximately 69 to 72 million years ago—there were several species living on several different continents. In this study of the preserved footprints found in Alaska, the researchers found evidence of both pack and family behavior.

The footprints were found on a piece of land not much bigger than a soccer field—scientists working there found thousands of preserved tracks from several types of animals and insects—all living during the during the Late Cretaceous. In this study, the emphasis was on the hadrosaurs.

The team found footprint size ranged from 8 to 64 centimeters, which they said could be attributed to dinosaurs of four different groups: adults, near-adults, juveniles, and the very young. The majority of the tracks were made by adults or those close to being full grown—84 percent. Very young members made up 13 percent of the tracks while juveniles made up just 3 percent of the total. Because the tracks appear to have been made near in time to one another, the researchers suggest they offer evidence that the dinosaurs lived as family units within a herd. The small number of juvenile tracks, they add, likely means that the dinosaurs had a very short juvenile period—they probably grew pretty fast because at that stage they would have been very vulnerable to predators. Also, it appears unlikely the small dinosaurs would have been able to migrate, thus the offer evidence that the dinosaurs lived in the Arctic year-round.

Scientists believe that the area in which the were found was more mild millions of years ago, likely closer to what is now typical for the Pacific Northwest, making it a suitable place for a hadrosaur to raise a family. The researchers note also that some of the tracks were so clear, it was possible to make out skin impressions, which offered clues as to what the bottoms of the feet looked like.

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More information: Herd structure in Late Cretaceous polar dinosaurs: A remarkable new dinosaur tracksite, Denali National Park, Alaska, USA, Anthony R. Fiorillo, Stephen T. Hasiotis and Yoshitsugu Kobayashi, Geology published online 30 June 2014; DOI: 10.1130/G35740.1 . http://geology.gsapubs.org/content/early/2014/06/26/G35740.1.full.pdf+html

Abstract
The discovery of a new tracksite of mostly hadrosaurid dinosaur footprints, made by a herd living in an ancient high-latitude continental ecosystem, provides insight into the herd structure and behavior of northern polar dinosaurs and perspective on populations of large-bodied herbivores in an Arctic greenhouse world. This tracksite occurs in the Upper Cretaceous Cantwell Formation in the Alaska Range (Denali National Park, Alaska, United States), and it is the largest tracksite known from this far north. Preservation of the tracksite is exceptional: most tracks, regardless of size, contain skin impressions and they co-occur with well-preserved plant fossils and invertebrate trace fossils of terrestrial and aquatic insects. Statistical analyses of the tracks show that individuals of four different age classes of hadrosaurids lived together in a large social group. Our research results independently corroborate the growth curve for hadrosaurids proposed by paleohistologists that suggests that these dinosaurs experienced a period of rapid growth early in their life history.

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User comments : 18

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philw1776
5 / 5 (1) Jul 10, 2014
Hadrosaurs, the penguins of the mesozoic! Who knew?
Oh wait! Arctic, not Antarctic, my bad.
alfsen
1.4 / 5 (10) Jul 10, 2014
Read between the lines, and this is more evidence against catastrophic anthropogenic global warming. It emphasizes the fact that, for at least 80% of Earth's history, the planet was warmer than it is now, in some cases much warmer. Life survived and thrived in a warmer environment.
ssmith
1 / 5 (1) Jul 10, 2014
It was on vacation and just visiting the area.
cjn
2.6 / 5 (5) Jul 10, 2014
Read between the lines, and this is more evidence against catastrophic anthropogenic global warming. It emphasizes the fact that, for at least 80% of Earth's history, the planet was warmer than it is now, in some cases much warmer. Life survived and thrived in a warmer environment.


One cannot possibly know the temperature of the planet for its entire existence to know that "80%" of the time it was warmer than today. We can infer by fossils and some geological formations what the temperature may have been, but not with any real certainty.
cjn
5 / 5 (3) Jul 10, 2014
I wouldn't be surprised if the ocean currents or other climate-influential processes of 70 MYA resulted in that area of Alaska to be significantly warmer than it is now, while being in the same general latitude as remains today. You can see the striking difference in temperature/climate between Newfoundland and the UK on opposite sides of the Atlantic and at roughly the same latitudes, heavily influenced by the gulf stream current.
Milou
2.1 / 5 (7) Jul 10, 2014
Those Duck-billed have a name. They are called Sara Pallin. Although, they have more intelligence and smarter than her.
Shitead
1 / 5 (1) Jul 10, 2014
Regardless of temperature, the Arctic of 70 mya had 3 solid months of total darkness, just like today. Hadrosaurs were totally unequipped to survive in such an environment. The article purports to show that the hadrosaurs did not migrate. Ergo, the locality of the fossil footprints could not have been nearly as far north as the authors presume. There are still many chapters to be written (and rewritten) in the saga of plate tectonics.
Doug_Huffman
1 / 5 (4) Jul 10, 2014
One cannot possibly know the temperature of the planet for its entire existence to know that "80%" of the time it was warmer than today.
The precise temperature does not need to be known to know that for most of the past the temperature has been as hot as is the core.
verkle
1 / 5 (8) Jul 10, 2014
I am very interested to see that enough people complained about my post, and it is now mysteriously deleted. I would have love to see good discussion around it.
InterestedAmateur
4.3 / 5 (12) Jul 10, 2014
@verkle - Maybe your God disagreed with you and deleted it, gods supposedly move in mysterious ways.
cjn
5 / 5 (4) Jul 10, 2014
The precise temperature does not need to be known to know that for most of the past the temperature has been as hot as is the core.


Within a billion years of formation, prokaryotes evolved, implying that at least 3.6 bn of 4.6 bn years of the Earth's history, there was liquid (or frozen) water on the Earth. The geological record corroborates the presence of liquid water oceans on the planet during this period. Simple math will tell you that comes out to a minimum of 75% of the Earth's history where the surface temperature had to be less than the 5,500 degrees Celsius, the temperature of the Earth's core. Otherwise, there would have been no liquid water.

Unless of course you are advocating for a "Young Earth" model. In that case, I'd tell you that a science site is probably not the best place for you to be trolling.
Bill589
2.6 / 5 (5) Jul 11, 2014
Milou shows how unintelligent he is by saying that Sarah Palin is unintelligent. If he did a little research, he'd know better.
mooster75
4.6 / 5 (9) Jul 11, 2014
Milou shows how unintelligent he is by saying that Sarah Palin is unintelligent. If he did a little research, he'd know better.

No, he shows how unintelligent he is by bringing stupid politics into a science discussion. Just as you do.
alfie_null
4.2 / 5 (10) Jul 11, 2014
I am very interested to see that enough people complained about my post, and it is now mysteriously deleted.

We all thank you for the hint on how to properly handle your anti-science trolls.
verkle
1 / 5 (9) Jul 11, 2014
Please don't call me names. Instead, please join in the real discussion.
You can be guaranteed I won't stoop to the level of many in calling other people names and attacking their character. Instead, I will focus on the issues at hand.
Vietvet
3.8 / 5 (10) Jul 11, 2014
Please don't call me names. Instead, please join in the real discussion.
You can be guaranteed I won't stoop to the level of many in calling other people names and attacking their character. Instead, I will focus on the issues at hand.


How do you expect a "real" discussion when you reject the fact of evolution? The evidence for evolution is overwhelming. Millions of species have gone extinct and been replaced by millions of new species. How do you account for that?
Vietvet
4.3 / 5 (6) Jul 11, 2014
Please don't call me names. Instead, please join in the real discussion.
You can be guaranteed I won't stoop to the level of many in calling other people names and attacking their character. Instead, I will focus on the issues at hand.


How to you expext a "real" discussion when you reject the fact of evolution. The evidence for evolution is overwhelming. Millions of species have gone extinct and have been replaced by millions of new species. How do you account for that?

TheGhostofOtto1923
4.4 / 5 (7) Jul 11, 2014
Regardless of temperature, the Arctic of 70 mya had 3 solid months of total darkness, just like today. Hadrosaurs were totally unequipped to survive in such an environment. The article purports to show that the hadrosaurs did not migrate. Ergo, the locality of the fossil footprints could not have been nearly as far north as the authors presume
Denali is below the arctic circle. Did you check a map?
How do you expect a "real" discussion when you reject the fact of evolution? The evidence for evolution is overwhelming
The deletion of poor verkles posts is an example of natural selection, not gods will. Verkle does not wish to engage in discussion. He never answers questions or comments he doesn't like. He refuses to acknowledge evidence which proves him wrong.

His sanctimony is typical of religionists who enjoy baiting people and then claiming their emotion, and his restraint, are proof of gods grace.

How phony.