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Biformites LINCK, 1949
Type ichnospecies:
Biformites insolitus LINCK, 1949
Diagnosis:
Narrow, vermiform, slightly tapering, horizontal, straight to curved structures with delicate, ideally bisymmetrically arranged, transversed elongate, or polygonal to round, positive or negative protuberances. Preserved as positive hyporeliefs (SCHLIRF, 2012: p. 193; see also LINCK, 1949: p. 44).
Derivation of name:
From Latin bi = double and forma = shape; “double-shaped”.
Remarks:
RINDSBERG (1994) saw Biformites as a younger synonym of Walcottia which again is regarded by UCHMAN (1998) as a younger synonym of Protovirgularia. According to SCHLIRF (2012), Biformites LINCK, 1949 has to be retained because of distinct morphological differences between the two ichnogenera. Protovirgularia is a plaited burrow consisting of obliquely arranged pads of sediment. Biformites on the other hand, is not a burrow in the strict sense, but rather represents impressions of bodyparts of the tracemaker. The transverse ornamentations are not sediment pads but rather the result of impressions, probably made by the ambulacrals of asterozoans, most likely ophiuroids (SCHLIRF 2012). The ichnogenera Zhadaichnus YANG & SONG, 1985 and Ophioichnus BELL, 2004 are considered to be younger synonyms of Biformites LINCK, 1949 (see KNAUST & NEUMANN, 2016).
Environment:
Although the Schilfsandstein complex (Stuttgart Formation) is traditionally interpreted as fluvial deposits, the interpretation of Biformites as produced by an asterozoan tracemaker (SCHLIRF 2012) and the associations with Kouphichnium (LINCK, 1949), suggests fully marine conditions of parts of the Stuttgart Formation.
Known Stratigraphic Range:
Middle Triassic (“Zhadaichnus” YANG & SONG, 1985); Upper Triassic (LINCK 1949; SCHLIRF 2012); Lower Cretaceous (“Ophioichnus“ BELL, 2004).
Known ichnospecies:
Detailed information for each ichnospecies
- Biformites insolitus LINCK, 1949
- Synonymy:
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*
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1949
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Biformites insolitus.
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- LINCK, p. 44; Pl. 4 1-2.
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non
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1994
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Walcottia rugosa, Biformites aspect.
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- RINDSBERG, p. 57; Pl 16 Fig. A [= Protovirgularia rugosa]
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2012
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Biformites insolitus.
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- SCHLIRF, p. 193; Fig. 8B, 9 A-C, 10 A-E.
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- Diagnosis: As for ichnogenus (monotypy) (SCHLIRF, 2012: p. 193; see also LINCK, 1949: p. 44).
- Orientation: Preserved as positive hypichnion.
- Morphological category (KNAUST, 2012): Imprints, although KNAUST (2012) interprets Biformites insolitus mainly as unbranched, passively filled burrow with a lining (following the synonymisation of RINDSBERG (1994) and UCHMAN (1998), SCHLIRF (2012) convincingly proofed Biformites to be originally a surface structure (imprint).
- Ethological category: Probably repichnia.
- Environment: Probably marine at the type locality (SCHLIRF 2012); in the Exeter Formation (Rhaetian of Pfrondorf near Tübingen, SW-Germany) marine beach facies (SEILACHER in LINCK 1949: p. 44).
- Derivation of name: From Latin insolitus = unaccustomed, peculiar, unusual.
- Types: Staatliches Museum für Naturkunde Stuttgart, Germany; Lectotype Inventary-No.: SMNS 22010; Paratypes Inventary-No.: SMNS 22010 (same slab as lectotype).
- Type locality: Maulbronn, Germany.
- Type horizon: Upper Triassic, Karnian, Middle Keuper, Stuttgart Formation, Upper Schilfsandstein.
- Geographical distribution: SW-Germany: Maulbronn (type locality); Freudenstein (both Karnian); Pfrondorf near Tübingen (Rhaetian). Tibet (“Zhadaichnus”) and Chile (“Ophioichnus”).
- Remarks: SCHLIRF (2012) suggested asterozoans (probably ophiuroids) as tracemaker of B. insolitus.
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