coarse, net-like structure. The trabecular bone itself is not sclerotic or enlarged. Cement lines and woven bone are absent and the cavity walls are lamellar. The macroscopic, radiologic, and microscopic appearances of this Jurassic bone pathology are those of haemangioma, rather than giant-cell tumour, aneurysmal bone cyst, cystic angiomatosis, haemangiopericytoma, haemangioendothelioma, osteoporosis, osteoblastoma, metastatic disease, or Paget’s disease (only the latter four have been reported in non-human species). Osteoporosis is characterised by thinning of trabeculae, not thickening. Giant-cell tumours, aneurysmal bone cysts, osteoblastomas, and haemangiopericytoma are expansile disorders with thin delicate traveculae. Cystic angiomatosis lesions are surrounded by a rim of slcerotic bone. Haemangioendothelioma (also called angiosarcoma and haemangioendothelial sarcoma) are characterised by thinned trabeculae and ill-defined margins. Lytic lesions of metastatic cancer are usually not as sharply defined as in this case and do not contain thick bridging trabeculae. Paget’s disease is associated with coarsening of trabecular patterns, typically with “blade of grass” fronts of resorption. Contrary to the unidirectional orientation of trabecular thickening in haemangiomas, that in Paget’s disease is not limited to a single plane. Paget’s disease is characterised by woven bone, in contrast to the pattern observed in the reported specimen. Although this is not the first time that the diagnosis of haemangioma has been considered in a dinosaur (Moodie, cited in ref 2), it is the first documentation. Originally misdiagnosed in Jurassic sauropods, speculation about the early occurrence of this vascular tumour is now substantiated. This appears to represent the earliest neoplasm in the geologic record.