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 ance ...

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 paleontologist and comparative anatomist. He has spent his career at the

Swedish Museum of Natural History The Swedish Museum of Natural History ( sv, Naturhistoriska riksmuseet, literally, the National Museum of Natural History), in Stockholm, is one of two major museums of natural history in Sweden, the other one being located in Gothenburg. The ...

Stockholm Stockholm () is the Capital city, capital and List of urban areas in Sweden by population, largest city of Sweden as well as the List of urban areas in the Nordic countries, largest urban area in Scandinavia. Approximately 980,000 people liv ...

Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...

, as curator at the Department of Palaeozoology. Bjerring's research is mainly about the fundamental structure of the

head A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may ...

in vertebrate evolution. His studies are based on detailed analyses of models of the crania of the sarcopterygian fishes '' Eusthenopteron foordi'' and ''Glyptolepis groenlandica'' from the

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...

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 ten ...

. He belongs to the Stockholm school of paleontology together with, among others, Erik Stensiö, Erik Jarvik, Gunnar Säve-Söderbergh, and

Tor Ørvig Tor Ørvig (27 September 1916 – 27 February 1994) was a Norwegian-born Swedish paleontologist who explored the histology of early vertebrates. He was professor at the Swedish Museum of Natural History in Stockholm and member of the Royal S ...

. A recurrent theme in Bjerring's research is that much of the vertebrate head is formed by a complex intertwining of serially

homologous Homology may refer to: Sciences Biology *Homology (biology), any characteristic of biological organisms that is derived from a common ancestor *Sequence homology, biological homology between DNA, RNA, or protein sequences * Homologous chrom ...

anatomical segments. According to Bjerring, this holds both for the distribution and composition of cranial nerves, the pharyngeal arches and their contributions to the

braincase In human anatomy, the neurocranium, also known as the braincase, brainpan, or brain-pan is the upper and back part of the skull, which forms a protective case around the brain. In the human skull, the neurocranium includes the calvaria or skul ...

organs and structures derived from the pharyngeal clefts as well as

muscle Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscl ...

s and

cartilages Cartilage is a resilient and smooth type of connective tissue. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck and ...

at the base of the skull. Bjerring has also discussed a number of classical problems in

comparative anatomy Comparative anatomy is the study of similarities and differences in the anatomy of different species. It is closely related to evolutionary biology and phylogeny (the evolution of species). The science began in the classical era, continuing in t ...

. Like Erik Jarvik, he has argued that the three ear ossicles of mammals can be derived from components of the hyoid branchial arch of

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 The evolution of mammalian auditory ossicles was an evolutionary event that resulted in the formation of the bones of the mammalian middle ear. These bones, or ossicles, are a defining characteristic of all mammals. The event is well-documented an ...

. Another classical problem is which one of two pairs of large dermal bones in the

skull roof The skull roof, or the roofing bones of the skull, are a set of bones covering the brain, eyes and nostrils in bony fishes and all land-living vertebrates. The bones are derived from dermal bone and are part of the dermatocranium. In comparati ...

of sarcopterygian fishes that is homologous to the parietal bone of tetrapods. 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 in therians, one of the bone pairs has been displaced and forms the tentorium cerebelli 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 ''Ichthyostega'' (from el, ἰχθῦς , 'fish' and el, στέγη , 'roof') is an extinct genus of limbed tetrapodomorphs from the Late Devonian of Greenland. It was among the earliest four-limbed vertebrates in the fossil record, and was on ...

'' and embryonic humans. Bichirs are a small group of aberrant

bony fish Osteichthyes (), popularly referred to as the bony fish, is a diverse superclass of fish that have skeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes, which have skeletons primarily composed of cartilag ...

whose anatomy has been explored by Bjerring. He identified a pair of intracranial

ligament A ligament is the fibrous connective tissue that connects bones to other bones. It is also known as ''articular ligament'', ''articular larua'', ''fibrous ligament'', or ''true ligament''. Other ligaments in the body include the: * Peritoneal li ...

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

temnospondyl Temnospondyli (from Greek language, Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') is a diverse order (biology), order of small to giant tetrapods—often considered Labyrinthodontia, primitive amphi ...

s ''

Selenocara ''Selenocara'' is an extinct genus of mastodonsauroid temnospondyl. The type species is ''Selenocara groenlandica'', described by Gunnar Säve-Söderbergh in 1935 on the basis of skull bones from the Lower Triassic Wordie Creek Formation of Gre ...

'' and ''Aquiloniferus'' from the Lower Triassic of East Greenland. 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