Genealogical speculations of a later date (presumably first suggested by the Danish historians
Jakob Langebek and
Peter Frederik Suhm) would make Thorgil son of the Viking
Styrbjörn the Strong, who in turn is depicted as son of
Olaf Björnsson, king of Sweden. Styrbjorn's wife in the sagas,
Thyra, was the daughter of
Harold Bluetooth, king of
Denmark and
Norway. No
primary source supports this theory and the theory itself is almost impossible to maintain because of the chronological inconsistencies. Little is recorded about Thorgils in historical texts outside of his place in the genealogy of his children or grandchildren. Thorgils'
cognomen Sprakalägg can be translated into English as "Break-leg" or "Strut-leg". The 12th-century English chronicler
John of Worcester reports in an entry dated 1049 that Earl
Beorn Estrithson was brother of King
Svein of Denmark, and son of Danish Earl Ulf, son of Spracling[us], son of Urs[us]. Here Spraclingus is a garbled representation of the byname of Thorgils appearing in later Scandinavian sources, while Ursus is the Latin
urso, or bear (
Bjørn in Danish,
Björn in Swedish). He appears in several 13th-century sources. He is Torgils or Þorgils Sprakaleggs in
Knýtlinga saga and in two works of
Snorri Sturluson –
Óláfs saga helga in
Heimskringla,) and was himself father of 'Thrugillus, called Sprageleg', father of Earl Ulf. Saxo further says of 'Thrugillis' that he "lacked not one ounce of his father's valour" (
nullo probitatis vestigio a paternae virtutis imitatione defecit). The other source,
Gesta Antecessorum Comitis Waldevi, copies the early generations of John of Worcester's pedigree but, confusing two like-named men, replaces Earl Beorn Estrithson as Earl Ulf's son with Björn Boreson, the father of
Siward, Earl of Northumbria. This pedigree commences with an episode not found in the Worcester chronicler's pedigree but similar to that of Saxo, that a 'certain nobleman', contrary to the natural order of human procreation, had a white bear as his father and a noblewoman as a mother, before continuing the pedigree with 'Ursus begat Spratlingus'. The chronicle sometimes attributed to the 15th-century
John Brompton tells a very similar tale of bear-paternity relating to the birth of Björn Boresune ('bear's son') himself. Historian Timothy Bolton has suggested that the role of a bear in the immediate ancestry of both Ulf's children and Siward's line may represent a tradition shared by relatives rather than that two independent families at about the same time both co-opting the same ancient Norwegian legend for their immediate ancestry – that Björn Boresune and Thorgils may have been brothers. depicted by sagas as the son of
Olaf Björnsson, king of Sweden. The sagas relate that Styrbjörn was the first husband of
Tyra, the daughter of
Harold Bluetooth, king of
Denmark and
Norway. Otto Brenner's detailed study of the descendants of
Gorm the Old gives his granddaughter Tyra and Styrbjörn no children. ==Children==