Collecting

The romance of dinosaurs is bound up with collecting: exotic and remote locales, heroic field conditions and the manly extraction of gargantuan beasts (see Chapter 14). But ultimately dinosaur collecting is a process that draws upon good planning, a strong geological background, and a bit of luck. The steps are:

1. planning;

2. prospecting; that is, hunting for fossils;

3. collecting, which means getting the fossils out of whichever (usually remote) locale they are situated; and

4. preparing and curating them; that is, getting them ready for viewing and incorporating them into museum collections.

Figure1.7. Supplies for one of the American Museum of Natural History's 1920s expeditions to the Gobi Desert. In the intervening 80 years, nobody has found a way to get around hauling the basic necessities into the field.

These steps involve different skills and sometimes different specialists. Planning

Collecting dinosaur fossils is not to be undertaken lightly. Dinosaur bones are - even in the richest sites - quite rare, and the moment they are disturbed the loss of important information becomes a concern. For this reason, most professional paleontologists have advanced degrees - often a Ph.D. in the geological or biological sciences - but before actually leading an expedition themselves, all have acquired many years of experience both in the logistical as well as the scientific ends of fieldwork.

Running an expedition. The logistical end of an expedition involves keeping one's team fed, watered, healthy, and happy in remote places where, in many cases, these don't come easily. Relentless sun, extreme heat, dust, lack of amenities, subsistence on a limited diet, and isolation from the "real world," all conspire to wear down even the most robust of people. It's all happening in the Great Outdoors, true, but it's nothing like a camping catalog! Add to these, language problems when you are working in other countries and limited access to medical facilities in the event of an accident involving either you or one of your crew, and the potential for disaster increases dramatically.

Many expeditions have to carry everything with them - fuel, water, food, all gear for the maintenance of daily life - as well as all the maps and equipment necessary to successfully carry out the science and safely retrieve heavy, yet delicate, dinosaur bones. This takes some serious planning and experience; you and your crew's lives may depend upon it (Figure 1.7). You have to know what you are doing.

Fossils generally, and dinosaurs in particular, are not renewable resources, which means that collecting a dinosaur is a one-shot deal: it must be done right, because we will never be afforded another chance to do it again. Any information that is lost - any piece of the fossil that is damaged - may be lost or damaged forever. For this reason, there are many regulations associated with collecting vertebrate fossils.

The most basic are the collection permits required for work on public lands. Obtaining the permits requires advanced planning because the agencies in charge of issuing the permits reasonably require detailed accounts of your plans before the process can go forward.

One important part of the permit-obtaining process, especially in the case of dinosaur fossils (which tend to be large and heavy), is the ultimate disposition of the fossils. Who gets them? Does that person or place have the proper resources - or even the space - to store, preserve, and make them accessible to scientists and the general public? How is all this to be accomplished? Most of the truly great collections and many of the most important dinosaur fossils are housed in major museums, such as the American Museum of Natural History (New York), the Yale Peabody Museum (New Haven, CT), Tyrrell Museum (Alberta), the Smithsonian (Washington, DC), the Natural History Museum (London), and the Musée National d'Histoire Naturelle (Paris). These institutions have the resources required for the care of important specimens and the data associated with them.

Work overseas - and paleontology generally involves a lot of travel, no matter where you live - generates a whole new level of administrative preparation. All of the problems described above are compounded by language barriers, by the necessity to obtain visas along with permits, by the logistics of preparing a field expedition in a foreign country, and by the necessity of arranging for the eventual disposition of the fossils. What country, after all, would gladly see its fossil resources dug up and exported elsewhere? It's a delicate balance, sometimes requiring the skills of a diplomat.

Science. All of that care expended upon all those logistics is meaningless unless our planning extends to the science as well. Paleontologists don't just go to weird places and grab bones. If they did, they'd lose, forever, essential information bearing upon four major problems:

1. What kind of environment was it in which the dinosaur was preserved (because it might have have lived somewhere else)?

2. Where did it live?

Oryctodromeus, a small herbivorous dinosaur first described in 2007, is a perfect example of the importance of geological context (Figure 1.8).

Here was an animal found fossilized in its own burrow. Had the important geological context not been properly interpreted, the burrow would not have been recognized and this animal's unusual behavior (for a dinosaur, at least), would have gone unappreciated.

So before even collecting the fossil, the locality - the area in which the fossil or fossils occur - must be mapped geologically, in a way that records the most information possible about the setting in which the fossil was found. This kind of information requires specialized geological study of the paleoenvironments, that is the ancient environments represented by the

Oryctodromeus Fossils
Figure 1.8. Fossil burrow of the dinosaur Oryctodromeus. Careful study of the sedimentary context of this dinosaur revealed the burrow.

rocks in which the fossils are found, as well as the geological context above and below the fossil. Usually this is accomplished by geological mapping and by detailed study of the sedimentary geology of the locality. Interpreting the ancient environment in which the bones came to rest commonly involves teaming up with sedimentologists - geoscientists with specialized knowledge of sedimentary rocks and the ancient environments that they preserve. This kind of teamwork allows paleontologists to develop the most complete picture of the fossils and the conditions in which they lived and died.1

A question that is commonly asked is "How do you know where the dinosaur fossils are?". The simplest answer is "We don't." There is no secret, magic formula for finding dinosaurs, unless it is long, hard hours of pre-expedition library time and careful assessment of potentially productive - that is, fossil-bearing - regions. On the other hand, a well-educated guess rooted in knowing something about the kinds of environment in which dinosaurs lived can greatly increase the odds of finding fossils.

Some basic criteria help the success of the search. These are:

1. Right rocks: the rocks must be sedimentary.

2. Right time: the rocks must be of the right age.

3. Living on the land: the rocks must be terrestrial.

Right rocks. Sedimentary rocks have the best potential to preserve dinosaur fossils. Indeed, sedimentary rocks form in, and represent, sedimentary environments, many of them places where dinosaurs lived and died. Dinosaurs are known from other types of rocks, but their fossils are most likely found in sedimentary rocks.

Right time. If the rocks you search were not deposited sometime between the Late Triassic and the Late Cretaceous, you won't find dinosaurs. Older and younger rocks may yield amazing fossil creatures, but not dinosaurs.

Living on land. Dinosaurs were terrestrial, that is non-marine, beasts through and through, which means that their bones will generally be found in rocks that preserve the remnants of ancient river systems, deserts, and deltas. However, dinosaur remains are also known from lake deposits and from near-shore marine deposits.

Many of the richest fossil localities in the world are in areas with considerable rock exposure, such as badlands. Fossil localities are common in deserts: plant cover on the rocks is low, and the dry air slows down the rates of weathering so that, once a fossil is exposed, it isn't chemically destroyed or washed away. Paleontologists, therefore, don't often find themselves in the jungle looking for fossils; the weathering rates are too high and the rocks are covered by vegetation. The chances of finding fossils are best in deserts, or at least fairly dry regions. Still, not all dinosaur material has been found in deserts. As long as the three criteria above are met, there is a possibility of finding dinosaur fossils, and that's usually reason enough for going in and taking a look.

Because fossils are a non-renewable resource, collecting them should be treated with the utmost circumspection. Poor planning, indifference to their significance, lack of training, and ignorance when retrieving them from the ground, will at best lose important data, and at worst place you and your team's lives in jeopardy.

1. The study of all that happens to an organism after its death is called "taphonomy," and is a specialized field combining sedimentology and paleontology. Understanding the taphonomy of a fossil is the best way to know whether the animal actually lived in the environment in which its fossils were found, or whether its carcass was just deposited there after death.

Was this article helpful?

0 0

Post a comment