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Records, extremes, and supremes endlessly intrigue. Biggest is especially fascinating—particularly when it is a huge meat-eating predator, mouth filled with deadly fangs, and a gape that could easily accommodate a human being. No wonder Tyrannosaurus is one of the world's best-known creatures, even though it perished 65 million years ago. Formerly famed as the biggest meat-eater in history, Tyrannosaurus has been challenged in recent years by a rash of newly discovered fossils which reveal even greater hunters.
When reconstructing dinosaurs, especially if they are potential record breakers, caution is key. This applies particularly to specimens where only small fragments remain—which, in paleontology, is the vast majority of cases. People naturally wish to focus on the extremes of estimates, rather than the more considered middle range of measurements. The following pages include several claimants to the throne of largest-ever land meat-eater. In some cases, there is a lack of fossil material for full assessment, and it is with caution that they should be hailed as newly crowned champions.
First with a Name
In 1824 Oxford scholar William Buckland (1784-1856) became president of the prestigious Geological Society of London. That same year he published an account of fossils discovered several years earlier in Stonesfield Quarry, near Oxford, England. He described several fossils as belonging to some form of large, long-gone reptile. Buckland named the beast Megalosaurus, "great lizard." This was the first scientific name bestowed ona dinosaur. However, Buckland knew nothing of this, since the term dinosaur would not be coined for another 18 years.
The fossils examined by Buckland included a length of lower jaw with teeth, some vertebrae (backbones), and assorted portions of a scapula (shoulder blade), pelvis (hip bone), and hind limb bones. The jaw was especially striking, with one long, sharp, fully grown mature tooth, and several shorter, younger, part-grown teeth.
These fossils were quite probably not from one individual, but two or more. They had already been examined by Georges Cuvier (1769-1832), the enormously influential French comparative anatomist and one of Europe's most respected scientists. On a visit to Buckland, Cuvier agreed that the remains represented a lizard-like reptile of some kind. At different times, Buckland variously estimated the length of Megalosaurus at 23 to 40 feet (7-12 m).
A Wastebasket Genus
Over the following decades, any fossils that remotely resembled a large meat-eating reptile were casually named Megalosaurus. The supposed geographic range of the "great lizard" spread as remains fitting its description were reported from France, Belgium, and Germany, then Portugal, and farther-flung regions. Eventually, alleged Megalosaurus fossils were being dug up in North America and even Australia. Thus the name Megalosaurus became a "wastebasket genus" for all these various fossils. To add to the confusion, early reconstructions showed Megalosaurus resembling a stiff-legged crocodile, with a low, midline, sail-like crest of skin between its shoulders—due to vertebrae from a different dinosaur, the spinosaur Altispinax, being drafted in as substitutes for missing Megalosaurus backbones.
In recent times, many of the so-called Megalosaurus specimens have been restudied and assigned to other genera.
For example, in 1964 one of the better-preserved English specimens was renamed Eustreptospondylus, and some of the North American remains are now regarded as Dilophosaurus.
Megalosaurus remains a generally poorly known, medium-large carnivore from Late Jurassic times in Europe. It was perhaps a cousin of North America's Allosaurus. At first glance its reconstruction might resemble Allosaurus or Tyrannosaurus in overall body form and posture. Megalosaurus was probably around 30 feet (9 m) in length and 1 ton in weight. Various trackways, or series of fossilized footprints, have been attributed to it, including some fine sets near Ardley, England, uncovered in 1997. These may show its progress across what is now the rolling Oxfordshire countryside.Extreme Dinosaurs. Copyright � by Steve Parker. Reprinted by permission of HarperCollins Publishers, Inc. All rights reserved. Available now wherever books are sold.