Hans Christian Bjerring (born May 30, 1931) is a

Danish Danish may refer to: * Something of, from, or related to the country of Denmark People * A national or citizen of Denmark, also called a "Dane," see Demographics of Denmark * Culture of Denmark * Danish people or Danes, people with a Danish a ...

Swedish Swedish or ' may refer to: Anything from or related to Sweden, a country in Northern Europe. Or, specifically: * Swedish language, a North Germanic language spoken primarily in Sweden and Finland ** Swedish alphabet, the official alphabet used by ...

vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () (chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with c ...

paleontologist Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...

and comparative anatomist. He has spent his career at the Swedish Museum of Natural History in Stockholm, Sweden, as

curator A curator (from la, cura, meaning "to take care") is a manager or overseer. When working with cultural organizations, a curator is typically a "collections curator" or an "exhibitions curator", and has multifaceted tasks dependent on the parti ...

at the Department of Palaeozoology. Bjerring's research is mainly about the fundamental structure of the head in vertebrate

evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

. His studies are based on detailed analyses of models of the crania of the

sarcopterygian Sarcopterygii (; ) — sometimes considered synonymous with Crossopterygii () — is a taxon (traditionally a class or subclass) of the bony fishes known as the lobe-finned fishes. The group Tetrapoda, a mostly terrestrial superclass includ ...

fishes '' Eusthenopteron foordi'' and ''Glyptolepis groenlandica'' from the Devonian as well as serially-sectioned embryos of fishes and

urodeles Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All t ...

. He belongs to the Stockholm school of paleontology together with, among others,

Erik Stensiö Prof Erik Helge Osvald Stensiö HFRSE (2 October 1891 – 11 January 1984) was a Swedish paleozoologist. He later took his new surname from his place of origin and is occasionally referred to with both names (as Erik Andersson Stensiö, Erik ...

Erik Jarvik Anders Erik Vilhelm Jarvik (30 November 1907 – 11 January 1998) was a Swedish paleontologist who worked extensively on the sarcopterygian (or lobe-finned) fish ''Eusthenopteron''. In a career that spanned some 60 years, Jarvik produced some ...

Gunnar Säve-Söderbergh Gunnar Säve-Söderbergh (31 January 1910 – 8 June 1948) was a Swedish palaeontologist and geologist. Säve-Söderbergh was born at Falun, the son of the neurologist Gotthard Söderbergh and Inga Säve. He passed his G.C.E. at Gothenburg i ...

, and Tor Ørvig. A recurrent theme in Bjerring's research is that much of the vertebrate head is formed by a complex intertwining of serially homologous anatomical segments. According to Bjerring, this holds both for the distribution and composition of

cranial nerves Cranial nerves are the nerves that emerge directly from the brain (including the brainstem), of which there are conventionally considered twelve pairs. Cranial nerves relay information between the brain and parts of the body, primarily to and f ...

, the

pharyngeal arches The pharyngeal arches, also known as visceral arches'','' are structures seen in the embryonic development of vertebrates that are recognisable precursors for many structures. In fish, the arches are known as the branchial arches, or gill arche ...

and their contributions to the braincase organs and structures derived from the pharyngeal clefts as well as muscles and cartilages at the base of the

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...

. Bjerring has also discussed a number of classical problems in comparative anatomy. Like

, he has argued that the three

ear ossicles The ossicles (also called auditory ossicles) are three bones in either middle ear that are among the smallest bones in the human body. They serve to transmit sounds from the air to the fluid-filled labyrinth (cochlea). The absence of the auditory ...

mammals Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur o ...

can be derived from components of the hyoid

branchial arch Branchial arches, or gill arches, are a series of bony "loops" present in fish, which support the gills. As gills are the primitive condition of vertebrates, all vertebrate embryos develop pharyngeal arches, though the eventual fate of these arc ...

osteolepiform Osteolepiformes, also known as Osteolepidida, is a group of prehistoric lobe-finned fishes which first appeared during the Devonian period. The order contains the families Canowindridae, Megalichthyidae, Osteolepididae and Tristichopteridae. Th ...

s rather than from both the mandibular and hyoid arches as claimed by the Reichert–Gaupp theory. Another classical problem is which one of two pairs of large

dermal bone A dermal bone or investing bone or membrane bone is a bony structure derived from intramembranous ossification forming components of the vertebrate skeleton including much of the skull, jaws, gill covers, shoulder girdle and fin spines rays ( le ...

s in the skull roof of

fishes that is homologous to the

parietal bone The parietal bones () are two bones in the skull which, when joined at a fibrous joint, form the sides and roof of the cranium. In humans, each bone is roughly quadrilateral in form, and has two surfaces, four borders, and four angles. It is nam ...

tetrapods Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids (reptiles, including dinosaurs and therefore birds) and synapsids ( pelycosaurs, extinct therapsi ...

. Here, Bjerring has proposed that neither alternative is correct; rather, the confusion may stem from the fact that, owing to the enormous expansion of the

telencephalon The cerebrum, telencephalon or endbrain is the largest part of the brain containing the cerebral cortex (of the two cerebral hemispheres), as well as several subcortical structures, including the hippocampus, basal ganglia, and olfactory bulb. In ...

theria Theria (; Greek: , wild beast) is a subclass of mammals amongst the Theriiformes. Theria includes the eutherians (including the placental mammals) and the metatherians (including the marsupials) but excludes the egg-laying monotremes. ...

ns, one of the bone pairs has been displaced and forms the

tentorium cerebelli The cerebellar tentorium or tentorium cerebelli (Latin for "tent of the cerebellum") is an extension of the dura mater that separates the cerebellum from the inferior portion of the occipital lobes. Structure The cerebellar tentorium is an arch ...

below the skull roof. He has also analysed the basic structure of the paired limbs by comparing the pectoral and pelvic fins of the ''

Eusthenopteron ''Eusthenopteron'' (from el, εὖ , 'good', el, σθένος , 'strength', and el, πτερόν 'wing' or 'fin') is a genus of prehistoric sarcopterygian (often called lobe-finned fishes) which has attained an iconic status from its close ...

'' with the hindleg of the Devonian tetrapod '' Ichthyostega'' and embryonic humans.

Bichir Bichirs and the reedfish comprise Polypteridae , a family of archaic ray-finned fishes and the only family in the order Polypteriformes .Helfman GS, Collette BB, Facey DE, Bowen BW. 2009. The Diversity of Fishes. West Sussex, UK: Blackwell Pu ...

s are a small group of aberrant bony fish whose anatomy has been explored by Bjerring. He identified a pair of intracranial ligaments that hold their brains in place, variations in the structure of the vomer, the structure of the olfactory organ in bichir embryos, and reported a spinobulbar cistern resembling the cerebellomedullar cistern of mammals. Bjerring has disputed the common view that bichirs are

actinopterygians Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or hor ...

, mainly because some alleged homologies between the cranial bones of bichirs and actinopterygians are dubious. Bjerring has named the

temnospondyl Temnospondyli (from Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') is a diverse order of small to giant tetrapods—often considered primitive amphibians—that flourished worldwide during the Carbo ...

s '' Selenocara'' and ''Aquiloniferus'' from the Lower

Triassic The Triassic ( ) is a geologic period and system (stratigraphy), system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Year#Abbreviations yr and ya, Mya), to the beginning of the Jurassic Period 201.36 ...

of East

Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland i ...

. His papers are richly illustrated and characterized by a pregnant, sometimes polemic style. He has also written popular scientific articles.Bjerring, H. C. (1989). Svalg- och gälspringor - deras ursprung och vidare öden. In: ''Naturen berättar. Utveckling och forskning vid Naturhistoriska riksmuseet'' (ed. K. Engström), pp. 131-140. Stockholm: Naturhistoriska riksmuseet. n Swedish./ref>

References

{{DEFAULTSORT:Bjerring, Hans C. Swedish paleontologists Paleozoologists Swedish scientists 1931 births Living people Swedish ichthyologists