Hans C. Bjerring

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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.

[edit] Scientific publications

Bjerring, H. C. 1967. Does a homology exist between the basicranial muscle and the polar cartilage? In: Problèmes Actuels de Paléontologie (Évolution des Vertébrés), Colloques Internationaux du Centre National de la Recherche Scientifique 163: 223-267.

Bjerring, H. C. 1968. The second somite with special reference to the evolution of its myotomic derivatives. In: Current Problems of Lower Vertebrate Phylogeny (ed. T. Ørvig), Nobel Symposium 4, pp. 341-357. Stockholm, Almqvist & Wiksell.

Bjerring, H. C. 1970. Nervus tenuis, a hitherto unknown cranial nerve of the fourth metamere. Acta Zoologica (Stockh.) 51: 107-114.

Bjerring. H. C. 1971. The nerve supply to the second metamere basicranial muscle in osteolepiform vertebrates, with some remarks on the basic composition of the endocranium. Acta Zoologica (Stockh.) 52: 189–225.

Bjerring, H. C. 1972a. Morphological observations on the exoskeletal skull roof of an osteolepiform from the Carboniferous of Scotland. Acta Zoologica (Stockh.) 53: 73-92.

Bjerring, H. C. 1972b. The nervus rarus in coelacanthiform phylogeny. Zoologica Scripta 1: 57–68.

Bjerring, H. C. 1972c. The rhinal bone and its evolutionary significance. Zoologica Scripta 1: 193-201.

Bjerring, H. C. 1973. Relationships of coelacanthiforms. In: P.H. Greenwood, R.S. Miles & C. Patterson (eds.), Interrelationships of fishes, pp. 179–205. Academic Press, London.

Bjerring, H. C. 1975. Contribution à la connaissance de la neuro-épiphyse chez les urodèles et leurs ancêtres porolépiformes, avec quelques remarques sur la signification évolutive des muscles striés parfois presents dans la region neuro-épiphysaire des mammifères. In: Problèmes Actuels de Paléontologie (Évolution des Vertébrés), Colloques Internationaux du Centre National de la Recherche Scientifique 218: 233-256.

Bjerring, H. C. 1977. A contribution to structural analysis of the head of craniate animals. The orbit and its contents in 20-22 mm embryos of the North American actinopterygian Amia calva L., with particular reference to the evolutionary significance of an aberrant, nonocular, orbital muscle innervated by the oculomotor nerve and notes on the metameric character of the head in craniates. Zoologica Scripta 6: 127–183.

Bjerring H. C. 1978. The 'intracranial joint' versus the 'ventral otic fissure'. Acta Zoologica (Stockh.) 59: 203-214.

Bjerring, H. C. 1979. Quondam gill-covers. Zoologica Scripta 8: 235-240.

Bjerring H. C. 1984a. The term 'fossa Bridgei' and five endocranial fossae in teleostome fishes. Zoologica Scripta 13: 231–238.

Bjerring H. C. 1984b. Major anatomical steps toward craniotedness: a heterodox view based largely on embryological data. Journal of Vertebrate Paleontology 4:17-29.

Bjerring H. C. 1985a. The question of a presupracleithrum in brachiopterygian fishes. Acta Zoologica (Stockh.) 66: 171-174

Bjerring, H. C. 1985b. Facts and thoughts on piscine phylogeny. In: Evolutionary Biology of Primitive Fishes (eds. R. E. Foreman, A. Gorbman, J. M. Dodd and R. Olsson), pp. 31-57. NATO Advanced Science Institutes Series A: Life Sciences, Vol. 103. New York, Plenum Press.

Bjerring, H. C. 1986a. The question of a dermohyal in brachiopterygian fishes. Acta Zoologica (Stockh.) 67: 1-4.

Bjerring, H. C. 1986b. Electric tetrapods? In: Studies in Herpetology (ed. Z. Roček), pp. 29–36. Prague, Charles University.

Bjerring, H. C. 1987. Notes on some annexa oculi in the osteolepiform freshwater fish Eusthenopteron foordi from the Upper Devonian Escuminac Formation of Miguasha. Acta Zoologica (Stockh.) 68: 173-178.

Bjerring, H. C. 1988. The morphology of the organum olfactus of a 32 mm embryo of the brachiopterygian fish Polypterus senegalus. Acta Zoologica (Stockh.) 69: 47-54.

Bjerring, H. C. 1989a. Apertures of craniate olfactory organs. Acta Zoologica (Stockh.) 70: 71- 85.

Bjerring, H. C. 1989b. Evolution of the tear duct. Plzeňsky Lékarsky Sbornik, Suppl. 59: 99-108.

Bjerring, H. C. 1991a. Some features of the olfactory organ in a Middle Devonian porolepiform, Glyptolepis groenlandica. Palaeontographica (A) 219: 89-95.

Bjerring, H. C. 1991b. Two intracranial ligaments supporting the brain of the brachiopterygian fish Polypterus senegalus. Acta Zoologica (Stockh.) 72: 41-47.

Bjerring, H. C. 1991c. The question of a vomer in brachiopterygian fish. Acta Zoologica (Stockh.) 72: 223-232.

Bjerring, H. C. 1993a. A reflection on the evolutionary origin of the tegmen tympani. Palaeontographica (A) 228: 129-142.

Bjerring, H. C. 1993b. Yet another interpretation of the coelacanthiform basicranial muscle and its innervation. Acta Zoologica (Stockh.) 74: 289-299.

Bjerring, H. C. 1994. The evolutionary origin and homologues of the supracochlear lamina: a contribution to our knowledge of mammalian ancestry. Acta Zoologica (Stockh.) 75: 359-369.

Bjerring , H. C. 1995a. The parietal problem: how to cut this Gordian knot? Acta Zoologica (Stockh.) 76: 193–203.

Bjerring, H. C. 1995b. The question of a homology between the reptilian processus basipterygoideus and the mammalian processus alaris. Palaeontographica (A) 235: 79-96.

Bjerring, H. C. 1997. The question of the Eotriassic tetrapod genus Wetlugasaurus in Greenland and thoughts on the fossa coniformis entopterygoidea. Meddelelser om Grønland, Geosciences 34: 1-25.

Bjerring, H. C. 1998. The fates of spiracular allostoses in mammals. Acta Zoologica (Stockh.) 79: 51–67.

Bjerring H. C. 1999. A new amphibious tetrapod from the Greenlandic Eotriassic. Meddelelser om Grønland, Geosciences 38: 1–42.

Bjerring, H. C. 2000a. On the so-called cavum orbitonasale. Acta Zoologica (Stockh.) 81: 167–175.

Bjerring, H. C. 2000b. The basicranial alar process: an evolutionary perspective. In: Ichthyology: Recent Research Advances (ed. D. N. Saksena), pp. 1-10. Enfield, New Hampshire, Science Publishers.

Bjerring, H. C. 2002. The anuran jaw apparatus in an evolutional light. Palaeontographica (A) 266: 93-119.