Hans C. Bjerring

From Wikipedia, the free encyclopedia

Hans Christian Bjerring (b. 1931) is a Danish-Swedish vertebrate paleontologist and comparative anatomist. He has spent his career at the Swedish Museum of Natural History in Stockholm, Sweden, holding the position as curator at the Department of Palaeozoology.

In 1956 Bjerring participated in an expedition to East Greenland where he, together with Erik Jarvik and Svend Erik Bendix-Almgreen, found specimens of the porolepiform sarcopterygian Glyptolepis groenlandica in a Middle Devonian sandstone exposure. Bjerring and Jarvik later studied its cranium using three-dimensional models based on serial sections.

A major theme in Bjerring’s research is serial homology in vertebrate organ systems, particularly of the head. He thus represents the segmentationist view of vertebrate head structure. Another theme is the functional shift of various anatomical structures in evolution. The origin of the intracranial joint of porolepiforms, osteolepiforms, and coelacanthiforms, the homology of cranial nerves, the homology of the parietal and parasphenoid bones, and typology of nostrils are among the morphological problems dealt with by Bjerring.

In 1985, Bjerring presented a reconstruction of the Devonian tetrapod Ichthyostega as an aquatic animal with paddle-like hindlimbs and somewhat curved back that anticipated more recent renditions. From 1985 onwards he also described thitherto unknown aspects of the anatomy of the bichir (Polypterus), including the first report of intracranial ligaments spanning the brain and of a spinobulbar cistern resembling the cerebellomedullar cistern of mammals.

In the 1990s, Bjerring turned to analysis of basicranial processes in mammals and reptiles and their possible homologues in Devonian sarcopterygian fish. He also suggested that the cerebellar tentorium of mammals may derive from the cephalic exoskeleton of lower vertebrates (the pluteal bones), resulting in the "parietal problem" in comparative anatomy.

Bjerring’s prose is rich in Graeco-Roman neologisms. Anatomical terms coined by him include anazygals, catazygals, jugular sanidium, tenuis and rarus nerves, janua, foris, tremiscus, spiracular scrobicle, basicranial ansilla, branchiothyrium, as well as glochinal, dacnil, melonic, and crepidine bones, and many others.

Few fossil taxa have been named by Bjerring, however; exceptions are the Lower Triassic temnospondyls Aquiloniferus and Selenocara. His papers from 1967 to 2002 are often lavishly illustrated.