Louis Dollo and the beasts of Bernissart

Louis Antoine Marie Joseph Dollo, a Belgian paleontologist with a name almost as luxuriant as his moustache, gave us our first true picture of dinosaurs, through an incredible preservation of articulated Iguanodon skeletons in Belgium (Figure B14.4.1). Born in Lille, France, in 1857, Dollo first pursued a career in civil engineering, but soon was hired by the Musee Royal d'H\sto\re Naturelle in Brussels, Belgium. Here he was in charge of the study and museum exhibition of these specimens.

In 1878, commercial coal miners identified fossil bone some 322 m (1,056 feet) below ground, which was immediately brought to the attention ofthe Brussels museum and to Dollo in particular. This occurrence ofbone turned into a treasure trove of more than 30 articulated skeletons of the Early Cretaceous ornithopod called Iguanodon (Figure B14.4.2).

Dollo's research on Iguanodon was unlike contemporary approaches, which tended to ask questions about to which taxon the material belonged and how it would be classified. Instead, thanks in part to the exquisite preservation of the Bernissart material, he devoted himselfto understanding the anatomy and function of these extinct forms in ways that had not been possible before. He sorted the Iguanodon material into two species by successively eliminating different sources of skeletal variation. He used the disparity between forelimb and hindlimb length, the development of ossified tendons across the back, and footprints to establish bipedality in Iguanodon. And he outlined new approaches to reconstructing the jaw systems of numerous dinosaurs including Iguanodon, putting them into their comparative context with living vertebrates. In doing so, Dollo turned paleontological attention to what he called "ethological paleontology" - the study of behavior and environment of extinct organisms - which Othenio Abel, a German paleontologist, termed paleobiology in 1912.

Dollo also worked on the other fossil forms from Bernissart, including its turtles, crocodilians, and amphibians.

Joseph Leidy
Figure B14.4.1. Louis Dollo (1857-1931), the Belgian paleontologist of the Musée Royale de Sciences Naturelles Belgiques, who, along with Joseph Leidy, Professor ofAnatomy at the University of Pennsylvania, first understood the shapes of dinosaurs.

When not busy with research on the riches ofBernissart, he conducted research on a number of new Late Cretaceous dinosaurs and mosasaurs from Belgium and elsewhere in the European lowlands, and on Antarctic fishes, among modern organisms.

Other than his work on Iguanodon, best known is Dollo's Law oflrreversible Evolution. This biological principle, which Dollo formulated in 1893, argued that evolution is not a reversible process. That is, structures eliminated during the course of evolution cannot themselves reappear in the same form within a given lineage of organisms.

Dollo died in his adopted home ofBrussels in 1931.

Figure B14.4.2. Several death-posed Iguanodon, the great beast of Bernissart, Belgium.

Figure 14.8. Seeley's evolutionary scenario of the origin of dinosaurs.

Figure 14.7. (a) Cambridge University's Harry G. Seeley (1839-1909) and (b) Friedrich von Huene (1875-1969), University of Tübingen.

SAURISCHIA

ORNITHISCHIA

PTEROSAURIA

Figure 14.7. (a) Cambridge University's Harry G. Seeley (1839-1909) and (b) Friedrich von Huene (1875-1969), University of Tübingen.

SAURISCHIA

ORNITHISCHIA

PTEROSAURIA

CROCODYLIA

Figure 14.8. Seeley's evolutionary scenario of the origin of dinosaurs.

CROCODYLIA

and likely three or four, separate origins within "thecodonts." Certainly, saurischians and ornithischians must have had separate origins; after all, their hip structure was different. And among saurischians, surely sauropods and theropods had separate origins; after all, they look so different. And finally, among ornithischians, ankylosaur ancestry was also often sought separately within some thecodontian group.

And what about Owen's bold suggestion that these dinosaurs were endothermic? Within ten or so years - and despite some early advocacy of it by other natural scientists - it was largely forgotten, the victim of the "fact" that dinosaurs were reptiles, and reptiles are cold-blooded.4 As late as 1953, Roy Chapman Andrews evocatively described T. rex's meal in cold-blooded - literally and figuratively - terms:

Then it [Tyrannosaurus] settles to the feast. Huge chunks of warm flesh, torn from the Duckbill's body, slide down the cave-like throat . . .The King's stomach

4. A few paleontologists, notably G. R. Wieland of Yale University, shared a vision ofsome kind ofdinosaur homeothermy.

is full to bursting. Walking slowly to the jungle, he stretches out beneath a palm tree . . .For days, or perhaps a week, he lies motionless in a death-like sleep. When his stomach is empty, he gets to his feet and goes to kill again. That is his life -killing, eating, and sleeping.5

Ironically - for how our views have changed! - this description would have appeared stranger to a nineteeth-century paleontologist like Cope or Marsh than to most paleontologists 70 years later. In retrospect, it seems puzzling that thoughtful scientists could have so meticulously described the bones and studied the relationships, yet with hardly any thought assumed "reptilian" ectothermy for dinosaurs for so long. Yet a look at publications through this period suggests that dinosaur metabolism rarely crossed their minds. Such is the strength of ideas.

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