Stringocephalus burtini

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Stringocephalus burtini
FMIB 48835 Stringocephalus Burtini Devonian.jpeg

Stringocephalus burtini

Temporal occurrence
Givetium
387.7 to 382.7 million years
Locations

Europe and Asia in the Neritic facies on the edge of the Paleotethys

Systematics
Rhynchonelliformea
Articulata
Terebratulida
Stringocephalidae
Stringocephalus
Stringocephalus burtini
Scientific name
Stringocephalus burtini
Defrance , 1825-1827

Stringocephalus burtini is a relatively large brachiopod with a beak-like protruding vertebra of the stalk valve from the order of the Terebratulida . In German-speaking countries, the species is therefore also known by its common name as "owl's head". Stringocephalus burtini is classically considered to be a conductor for the upper Middle Devonian ( Givetium ).

Etymology and history on taxonomy

The genus name Stringocephalus ( Sandberger 1842) is derived from the ancient Greek στρίγξ (strinx - night bird, owl) and the ancient Greek κεφαλή (kephalē - head).

The species name burtini is already used by Defrance in his first description of 1827 (" strigocéphale de Burtin, strigocephalus Burtini ") and is a homage to the Dutch-Belgian doctor and naturalist François-Xavier de Burtin (1743-1818)

There are often different variants of the full scientific name in the specialist literature, such as:

  • Stringocephalus burtini (Defrance, 1825)
  • Stringocephalus burtini (Defrance in Blainville, 1825)
  • Stringocephalus burtini (Defrance, 1827)
  • Stringocephalus burtini (Defrance in Blainville, 1827)
  • Stringocephalus burtini (Defrance, 1825–1827)

Etc.

A treatise by the Austrian geologist Eduard Suess from 1853 already provides a first indication of the cause of these different spellings. Suess remarks:

“If you disregard the very dubious figure in Schlotheim's Petrefactenkunde, […], […], it was Defrance first, in 1827 in the 51st volume of Dictiotin. de sciences nature. p. 102 set up this family and already added a drawing of the castle, both large septa, and the so-called bridge to the illustrations; the specimens were from Chimay in Belgium. - In 1825 Blainville (Manuel d. Malacol. P. 511. t. LIII.) Copied the figures of Defrance, but united Strygocephalus as a subdivision with Terebratula. "

- Suess : To the knowledge of the Stringocephalus Burtini Defrance

In fact, in the text volume of the "Manuel de Malacologie et de Conchyliologie" from 1825, only a very rudimentary short description appeared with a reference to the illustrations in the accompanying table volume. The latter, however, did not appear until 1827, almost at the same time as a more detailed description in the “Dictionnaire des Sciences Naturelles”. Strictly speaking, the individual entries in “Manuel de Malacologie et de Conchyliologie” are to be assessed as nouns nudum , so the spelling “ Stringocephalus burtini (Defrance, 1825–1827)” is preferred and reference is made to all three quotations.

The position of Stringocephalus burtini as a representative of an independent genus Stringocephalus was long disputed in the 19th century. Then the pendulum jumps in the opposite direction and all similar shapes are classified as Stringocephalus burtini , as Cloud criticized in 1942 . Only a comprehensive analysis by Struve , 1992 brought some order to the chaos. Therefore, especially when studying older specialist literature, caution is advised as to which species is actually meant.

features

Stringocephalus burtini in dorsal view (top left), ventral view (top right) and posterior view (bottom left). Yale Peabody Museum of Natural History; YPM IP 068209.

Unless otherwise stated, the description is based on Cloud , 1942.

External shape of the shells and internal structure

Stringocephalus burtini is a relatively large brachiopod whose shells can reach a diameter of up to 11 cm. The two flaps of the bowl are roughly as long as they are wide, have a rounded outline and are strongly convex. The outside of the shell is smooth and, apart from concentric strips of growth, largely unsculptured.

The front part of the commissure line (frontal margin) is straight (rectimarginat); Sinus and bulge are not present. The lock edge is evenly curved. The stalk valve ( ventral valve ) has a strongly protruding, beak-like, inwardly curved vertebra. The stalk hole (foramen) is round to oval and lies in the middle of the deltidium (“hypothyrid”).

The internal structure of the shells is, as with all representatives of the Terebratulida, punctate .

Stringocephalus burtini in stone core preservation . The constriction through the median septum of the arm valve is clearly visible on the upper side.

Inner shell features

Both the pedicle valve ( ventral valve ) and the arm valve ( dorsal valve ) have a keel-like projecting median septum in the middle on the inside. The median septum of the pedicle valve is stronger and longer than that of the arm valve.

The arm structure (brachidium) is loop-shaped (ancylopegmat) and, lying far outside, runs largely parallel to the shell edge of the arm valve. From the inner edge of the loop, spiky outgrowths run inwards ("stringocephalid arm framework"). Related forms, such as B. Stringocephalus gubiensis from the lower Central Devonian ( Eifelium ) of southern China, these spike-like extensions are missing on the arm frame loop .

The lock extension from the arm flap is unusually long and almost reaches the inside of the handle flap. The end of the lock process is deeply cut and forked to provide space for the median septum of the pedicle valve.

Starting from the foramen, the stalk is partially encased inward by a calcitic tube (syrinx).

Color pattern of the shell

In 1988, Blodgett et al. from the Givetium of southern England specimens of Stringocephalus burtini in shell preservation which still showed remains of a color pattern. Complex patterns of concentric and radial bands of color have been proven.

Ontogenetic evolution and paleoecology

Detailed investigations on more than 200 individuals of Stringocephalus burtini from the Holy Cross Mountains in Poland allow conclusions to be drawn about the ontogeny and, in some cases, the way of life of the brachiopod species. The size of the shells examined ranged from approx. 0.7 mm to several cm. The main development trends are:

  • In individuals <2.5 mm, the interlocking process is not a forked individual structure, but consists of two clearly separated, independent individual processes that only unite in the further course of growth.
  • In juvenile specimens with a shell diameter of up to 6 mm, the vertebra of the pedunculate valve is unusually large (up to 52% of the total shell length) and not yet strongly curved inward.
  • The stem opening is wide open in juvenile forms and grows increasingly closed in the course of individual development; in gerontic individuals it is completely closed and non-functional.

From these developmental tendencies it can be concluded that young animals were initially attached to the substrate with their stalk, but then loosely rested on the substrate in the further course of individual development. The initial orientation was with the arm flap resting on the substrate. In the case of many fossils in a living position, however, it can also be determined that the animal was resting with the handle flap on the substrate and has changed its orientation either due to the current or its own activity. Due to the strongly biconvex shell shape and a center of gravity far back, an orientation of the shell opening that was favorable for the spinning of food was probably given in both cases, so that the animal probably did not suffer any significant disadvantage from the twisted orientation.

Stringocephalus burtini was a typical inhabitant of the tabulates - stromatopore reefs of the Central Devonian. Due to its size and its thick shells, the brachiopod was initially mistaken for an inhabitant of the turbulent reef core area. More recent sedimentological and microfacial investigations, as well as the above-mentioned observations on ontogenesis , however, indicate that the original habitat is rather in the somewhat calmer waters of the rear reef or the lagoon, not far behind the actual reef. Layers of accumulation of (often broken) Stringocephalus shells, which indicate a stronger movement of the water column, are now usually interpreted as the result of short-term storm events ( Tempestite ).

Distribution and usefulness as a guide fossil

Documented sites of Stringocephalus burtini extend from the south of England and the north of France over the Ardennes of Belgium ( type locality ), the mass limes ("Stringocephalus layers") of the Rhenish Slate Mountains , the Holy Cross Mountains of Poland, the Carnic Alps in the border area Austria / Italy, to South China and Vietnam.

A continuous phylogenetic line of development from Stringocephalus gubiensis ( Eifelium ) via Stringocephalus burtini ( Givetium ) to Stringocephalus obesus (Givetium) was proposed for the representatives of the genus Stringocephalus from South China .

Stringocephalus burtini is considered to be a classic index fossil for the upper Central Devonian (Givetium). At times, the Givetium was actually defined by the first appearance or disappearance of Stringocephalus burtini . However, advances in conodont stratigraphy led to a redefinition of the stage, which is now limited by the first appearance of the conodonts Polygnathus hemiansatus (border Eifelium-Givetium) and Ancyrodella rotundiloba or Polygnathus asymmetricus (border Givetium- Frasnium ).

Comparisons with the much more detailed conodont stratigraphy have shown that Stringocephalus burtini in the givetium usually only appears well after the first appearance of Polygnathus hemiansatus , but that the occurrence may continue into the lowest frasnium. Due to its wide distribution in the Neritic facies of the Central Devonian of Europe and Asia and its characteristic features, Stringocephalus burtini is still of importance as a facies guide fossil.

literature

Web links

Commons : Stringocephalus burtin  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b c d M. Defrance: Strigocéphale In: FG Levrault (Editor): Dictionnaire des Sciences Naturelles , Volume 51, p. 102, 1827. (online)
  2. ↑ a b M. Defrance: In: HMD de Blainville: Manuel de Malacologie et de Conchyliologie , Tome 1, p. 511, 1825. (online)
  3. ↑ a b M. Defrance: Strygocéphale de Burtin In: HMD de Blainville: Manuel de Malacologie et de Conchyliologie , Tome 2, Plate LIII, 1827. (online)
  4. ^ G. Sandberger: Preliminary overview of the peculiar younger limestone layers of the older (so-called transitional) formation occurring near Villmar an der Lahn, especially according to their organic inclusions, and description of their most important new species; together with a foreword about naming in the description of nature in general and in palaeontology in particular, panel VIII, B. In: New Yearbook for Mineralogy, Geognosy, Geology and Petrefactuality , Volume 1842, pp. 379–402, 1842. (online)
  5. ↑ L. Koch: Fossils from the GeoPark Ruhrgebiet: "Eulenkopf" and "Greifenklaue" from the Middle Devon In: GeoPark Ruhrgebiet News, 1, pp. 18-19, 2013. (online)
  6. ↑ P.-J. Van Beneden: BURTIN, François-Xavier In: Biographie Nationale de Belgique , Tome 3, pp. 169–176, 1872. (fr.wikisource)
  7. ↑ a b c E. Suess: To the knowledge of the Stringocephalus Burtini Defrance. In: Negotiations of the Zoological-Botanical Association , Vol. 3, pp. 155–164, 1853. (digitized version )
  8. ^ A b P. Cloud: Terebratuloid Brachiopoda of the Silurian and Devonian . In: Geological Society of America Special Publ. 38 , pp. 107f, 1942.
  9. ↑ : W. Struve: News on the stratigraphy and fauna of the rhenotypic Middle Devonian. In: Senckenbergiana Lethaea , Volume 71, No. 5/6, pp. 503-624, 1992.
  10. ^ A b A. Balinski: Stringocephalus burtini Defrance from the Environs of Siewierz, Poland In: Acta Palaeontologica Polonica , Vol. XVI, No. 4, pp. 461–469, 1971. (digitized version )
  11. ^ A b c d e f A. Balinski: Morphology and Paleoecology of Givetian Brachiopods from Jurkowice-Budy (Holy Cross Mountains, Poland). In: Acta Palaeontologica Polonica , Vol. XVIII, No. 3, pp. 269-303, 1973. (digitized version )
  12. ↑ U. Lehmann & G. Hillmer: Invertebrates of prehistoric times - Guide to the systematic paleontology of invertebrates. P. 194, Enke, 1988
  13. ↑ U. Lehmann: Paleontological Dictionary P. 366 & Fig. 12 P. 54, Enke, 1977
  14. ↑ a b c Y. L. Sun & AJ Boucot: Ontogeny of Stringocephalus gubiensis and the Origin of Stringocephalus In: Journal of Paleontology , Volume 73, No. 5, pp. 860-871, 1999. (online)
  15. ↑ a b R. B. Blodgett, AJ Boucot & WF Koch: New Occurrences of Color Patterns in Devonian Articulate Brachiopods. In: Journal of Paleontology , Vol. 62, No. 1, pp. 46-51, 1988.
  16. ↑ RB Blodgett & VV Baranov: Alaska Fossil of the Month - Strinogocephalus and Omolonia (Members of the Brachiopod Subfamily Stringocephalinae) In: Alaska Geology - Newsletter of the Alaska Geological Society . Vol. 42, no. 7, pp. 6–9, 2012 (digitized version)
  17. ^ A. Balinski, Y. Sun & AJ Boucot: Heterochrony in Stringocephalus In: Journal of Paleontology , Volume 74, No. 6, pp. 1181–1183, 2000 (digitized version)
  18. ^ A b M. E. Schudack: Carbonate cycles in reef and lagoon areas of the Devonian mass limestone complex of Asbeck (Hönnetal, Rheinisches Schiefergebirge). In: Geology and Palaeontology in Westphalia , Issue 26, pp. 77-106, 1993. (digitized version )
  19. ↑ D. Brice: Brachiopod assemblages in the Devonian of Ferques (Boulonnais, France) - Relations to palaeoenvironments and global eustatic curves. In: Bulletin of Geosciences , Vol. 78, No. 4, 405-417, 2003 (digitized version )
  20. ^ LH Kreutzer: microfaces, stratigraphy and paleogeography of the central Carnic main ridge between Seewarte and Cellon. In: Yearbook of the Federal Geological Institute , Volume 133, Issue 2, pp. 275–343, 1990. (digitized version )
  21. ↑ T.-D. Thanh, TH Phuong, J. Philippe, NH Hung, NTT Cuc & NT Duong: Silurian and Devonian in Vietnam —Stratigraphy and facies. In: Journal of Geodynamics, Volume 69, pp. 165–185, 2013. (manuscript version)
  22. ^ A b O. H. Walliser, P. Bultynck, K. Weddige, RT Becker & MR Hous: Definition of the Eifelian - Givetian Stage boundary. In: Episodes , Volume 18, No. 3, pp. 107-115, 1995. (digitized version )
  23. ↑ Ch. Errenst: Colony-forming Phillipsastreidae and Hexagonariinae from the Givetium of the Messinghausen Saddle and from the southern edge of the Brilon mass limestone (northeastern Sauerland). In: Geology and Palaeontology in Westphalia , Issue 26, pp. 7–45, 1993. (digital copy )