研究人员已经在阿拉斯加半岛发现了许多恐龙足迹——这片狭长的土地从该州西南部延伸了大约500英里。
德克萨斯州佩罗自然科学博物馆的安东尼·菲奥里罗领导的一个小组记录了该州最大城市安克雷奇西南420英里处偏远的阿尼亚克国家自然保护区的脚印。
根据发表在开放存取期刊《PLOS一号》上的一项研究，这些痕迹被发现保存在所谓的奇格尼克组——一系列大约1650到2000英尺厚的海岸沉积物，可以追溯到白垩纪晚期(1.005-6600万年前)。)
研究人员在2001-2002年和2016-2018年间对该遗址进行了调查，确定了超过75个恐龙足迹遗址，其中包括几十个脚印。
该小组说，这一发现意义重大，因为尽管在阿拉斯加各地——特别是在德纳里国家公园和北坡等地——发现了恐龙化石，但在阿拉斯加半岛很少有关于这些古代动物的记录。
研究人员分析了他们发现的指纹，鉴定出两种属于装甲恐龙，一种来自食肉霸王龙，另外几种可能是由两种鸟类制造的。鸟类本质上是鸟类恐龙，因为它们是唯一幸存于6600万年前白垩纪末期大规模灭绝事件的恐龙谱系。
阿拉斯加半岛记录的Hadrosaur脚印。FIORILLO等人，2019年
然而，绝大多数的轨道(93%)属于一群食草的鸭嘴龙，被称为“鸭嘴龙”——意思是“庞大的蜥蜴”
这些动物长约10至65英尺，在灭绝前非常成功，科学家认为它们是生活在地球高纬度地区最常见的恐龙。
研究人员说，大量hadrosaur足迹表明，阿拉斯加这一地区的这些动物更喜欢沿海栖息地——这一结论反映了以前阿拉斯加北部研究的类似发现。
费奥雷洛在一份声明中说:“我们的研究向我们展示了一些恐龙对栖息地的偏好，以及鸭嘴恐龙极其丰富。”。“鸭嘴龙和牛一样常见，尽管我们在阿拉斯加工作，也许最好把它们看作白垩纪的驯鹿。”
这项研究的作者总结说，通过观察这些动物的迁徙模式，更多地了解鸭嘴龙的栖息地偏好有助于揭示生态系统是如何随着时间而变化的。
NUMEROUS DINOSAUR FOOTPRINTS DISCOVERED IN REMOTE ALASKAN PENINSULA
Researchers have identified numerous dinosaur tracks in the Alaskan Peninsula—a strip of land which extends for about 500 miles from the southwest part of the state.
A team led by Anthony Fiorillo from the Perot Museum of Nature and Science in Texas documented the footprints in the remote Aniakchak National Monument nature preserve, around 420 miles southwest of Anchorage, the state's largest city.
According to a study published in the open-access journal PLOS ONE, the tracks were found preserved in the so-called Chignik Formation—a series of coastal sediment deposits approximately 1,650 to 2,000 feet thick which dates back to the Late Cretaceous Period (100.5-66 million years ago.)
The researchers conducted investigations of the site between 2001-2002 and 2016-2018, identifying more than 75 dinosaur track sites which included dozens of footprints.
The discovery is significant, the team say, because while dinosaur fossils have been found across Alaska—particularly in places such as Denali National Park and the North Slope—there are very few records of these ancient animals in the Alaskan Peninsula.
The researchers analyzed the prints that they found, identifying two belonging to armored dinosaurs, one from a carnivorous tyrannosaur, and several others which were likely made by two types of birds. Birds are essentially avian dinosaurs given that they were the only dinosaur lineage to survive the mass extinction event which occurred at the end of the Cretaceous Period, 66 million years ago.
Hadrosaur footprints documented in the Alaskan Peninsula.FIORILLO ET AL, 2019
However, the vast majority of the trackways (93 percent) belonged to a group of herbivorous duck-billed dinosaurs known as "hadrosaurs"—which means "bulky lizards."
These animals—which ranged in length from around 10 to 65 feet—were highly successful before going extinct and scientists think that they were the most common dinosaurs living in regions located in Earth's higher latitudes.
The researchers say that the abundance of hadrosaur tracks suggests that these animals in this part of Alaska preferred coastal habitats—a conclusion which mirrors similar findings from previous research in the north of Alaska.
"Our study shows us something about habitat preferences for some dinosaurs and also that duck-billed dinosaurs were incredibly abundant," Fiorillo said in a statement. "Duck-billed dinosaurs were as commonplace as cows, though given we are working in Alaska, perhaps it is better to consider them the caribou of the Cretaceous."
The authors of the study conclude that understanding more about the habitat preferences of hadrosaurs could help to shed light on how ecosystems changed through time by looking at the migration patterns of these animals.
