ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Diggin' For Dinosaurs - Purgatoire River Trackway

Updated on March 30, 2010

At the bottom of a canyon in southern Colorado, where the Purgatoire River cuts through shale and limestone deposits that were laid down some 150 million years ago, visitors can see one of the most remarkable dinosaur sites in the world. With more than 1,300 footprints embedded in the ground, representing the travels of more than 100 animals, the Purgatoire site is the largest mapped dinosaur footprint area in North America.

Although local residents knew of the trackway since at least the 1920s - some called it "Elephant Crossing" - not until 1935 was the site brought to the attention of scientists. A schoolgirl named Betty Jo Riddenoure told her science teacher about the tracks, and this prompted the first scientific expedition to the site. In 1938, palaeontologists decreed that the tracks had been made by brontosaurs, making them the first such tracks ever reported. But perhaps because of their remoteness, the Purgatoire tracks were largely forgotten for nearly half a century, until researchers at the University of Colorado studied and mapped them in the early 1980s.

Most of the tracks now skirt the edge of the Purgatoire River. But the presence of fossilized plants, mollusks, fish, and crustaceans suggests that in the Jurassic, the area was a lake basin perhaps six miles wide. Dinosaur Lake, as palaeontologists call it, sported a semiarid climate similar to the savannas of East Africa today, and, judging by the alternating deposits of shale and limestone, the lake experienced seasonal or longer term fluctuations in water level. Scientists say the shale layers were laid down as mud in times of high water, while the limestone layers were deposited as coarser sediments along the lakeshore when water levels were low.

Because their tracks all appear in the limestone, the dinosaurs apparently liked to wander the edge of the lake and perhaps wade in shallow water. Today their tracks appear as clearly defined cavities in four different layers of hard limestone, stretching about a quarter mile along the river. About 60 percent of the tracks are believed to have been left by Apatosaurus visiting the lake. These plant eating animals stood 14 feet or taller at the shoulder and weighed 33 tons or more. Their roundish footprints, some two to three feet long, look like a series of highway potholes; they undoubtedly gave rise to the "Elephant Crossing" nickname.

The rest of the footprints are smaller and clearly belong to a different animal: Each is an oblong base topped with three rather sinister looking claw marks. Those tracks, say the scientists, were left by smaller theropods, meat eating dinosaurs like Allosaurus. The size of most two legged dinosaurs can be readily estimated using such tracks. Hip height is generally about four to five times the track length, so the theropods that roamed about Dinosaur Lake stood from two to eight feet tall at the hip. Those animals, although they weighed much less than the sauropods, were quite fast and ferocious and probably preyed on the huge plant eaters.

Continued in: Diggin' For Dinosaurs - Purgatoire River & Dinosaur Ridge

Back To Start

Comments

    0 of 8192 characters used
    Post Comment

    • Greensleeves Hubs profile image

      Greensleeves Hubs 

      6 years ago from Essex, UK

      All of your hubs on dinosaur fossil sites and dinosaur museums are excellently written Hal and offer loads of useful information to anyone in the vicinity of these places. This one I particularly like for the quality of writing and for the description of what life was like for the creatures which created these fossil footprints so long ago.

      With this in mind I am promoting this (and others of your hubs) in a review I am shortly going to be publishing on the HubPages website. In the meantime, I will happily vote up this particular hub. Sorry to see you're not writing on this site any more. Alun.

    • BL Tween profile image

      BL Tween 

      8 years ago

      Today their tracks appear as clearly defined cavities in four different layers of hard limestone, hummmm that is very interesting. Thanks for the info.

    working

    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, hubpages.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://hubpages.com/privacy-policy#gdpr

    Show Details
    Necessary
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Features
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Marketing
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Statistics
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)