JURASSIC PARKWAY VERSUS TRICERATOPS SUBURBS: FIELD COURSE FOR AMATEURS SEPARATE RESIDENT DINOSAURS FROM TRANSIENTS

Where did dinosaurs feed? Can we distinguish residents from transients? Skeleton concentrations may result from bloated carcasses floating in from disparate habitats. Most dinosaurs, except birds, shed teeth all through life. Shed crowns, if they are free of abrasion from long-distance stream transport, should indicate that feeding was performed nearby. Thus shed teeth join with coprolites as markers of feeding activity. In a twenty year study, our amateur short courses have censused large samples of bones and shed teeth from latest Jurassic Morrison Formation, Albany County, WY. Evaporites and thick caliche indicate severe aridity, suggesting that plant productivity was poor at times, suppressing herbivore feeding. The dinosaur skeletal sample is 82% sauropod herbivores, mostly diplodocid and camarasaurid. In contrast, sauropods contribute only 2% of the shed teeth, confirming the suspicion that the bones represent transients. Sauropod shed teeth are far more abundant in some Cretaceous sediments, e.g. the Cloverly Formation and Trinity Group, that are weaker in caliche and evaporites. The classic sauropod skeleton beds of Wyoming, however, may have been less “Jurassic Park” and more “Jurassic Parkway”.

In Wyoming, the Latest Cretaceous Lance Formation dinosaur-bearing sediments are swampy facies, dark units full of vegetable fragments; caliche and evaporites are very rare. Therefore we’d expect high plant productivity and evidence of intensive feeding. Our short courses sampled the Lance at Glenrock, WY. Triceratops and close kin provide 67% of the bones, and 83% of shed dinosaur teeth. Therefore we conclude that Triceratops was indeed a resident mega-herbivore. Pedal anatomy confirms the conclusion. Triceratops hind feet were large with four spreading toes, and so appear to be adapted for soft, swampy terrain. We are persuaded that reconstructions of community organization and feeding adaptation in dinosaurs do benefit from analyses of shed crowns. Such analyses require thousands of hours of careful field work, and field courses for motivated amateurs can supply the precision person-power.