Before Plates

©Pavel Riha

The origins of the thyreophorans are rarely discussed, in my personal circles, but the basal members of the family are strange and interesting even before the family developed large armored plates and skeletons. One of the earliest comes from the Early Jurassic approximately 196 million years ago. The remains of the dinosaur Scutellosaurus lawleri (Colbert 1981) were recovered from Arizona by David Lawler. The early thyreophoran was very small compared to its descendants, weighing in at approximately 3.9 feet long, 20 inches tall, and about 22 pounds. Covered in primitive versions of dermal armor scutes, Scutellosaurus was a small fully armored dinosaur that was capable of defending itself against similar sized predatory dinosaurs but not significantly against larger and stronger dinosaurs that could get around the dermal armor by crunching through with high enough bite forces. Determining how strong those scutes and armors are might take more than this week but we can certainly try to get into the topic.