Gastornis parisiensis Hébert, 1855

Bourdon, Estelle, Mourer-Chauviré, Cécile & Laurent, Yves, 2016, Early Eocene birds from La Borie, southern France, Acta Palaeontologica Polonica 61 (1), pp. 175-190 : 176-182

publication ID	https://doi.org/ 10.4202/app.00083.2014
persistent identifier	https://treatment.plazi.org/id/03BC87C4-FFAE-976F-FFE4-F8B56A02F8C3
treatment provided by	Felipe
scientific name	Gastornis parisiensis Hébert, 1855
status

Treatment

Figs. 1–4 View Fig View Fig View Fig View Fig .

Referred material.—MHNT.PAL.2013.15.1, maxilla; MHNT. PAL.2013.15.2,rightosquadratum;MHNT.PAL.2013.15.3–8,

six vertebrae cervicales; MHNT.PAL.2013.15.9, shaft of left femur; MHNT.PAL.2013.15.10, left tibiotarsus; APSO.2006. SP1-62, right tibiotarsus; from La Borie, Saint-Papoul, department of Aude, southern France; middle Ypresian, early Eocene, age close to reference level MP8–9.

Measurements (in mm).—Maxilla MHNT.PAL.2013.15.1: height, 166.0; length as preserved, 178.0; distance between rostral margin of right apertura nasi ossea and apex of rostrum maxillare, 100.0; distance between dorsal margin of right apertura nasi ossea and culmen, 93.2; distance between ventral margin of right apertura nasi ossea and crista tomialis, 54.0; length of right apertura nasi ossea, 34.0; height of right apertura nasi ossea, 17.0. Quadratum MHNT.PAL.2013.15.2: height, 77.0; width of processus oticus, 35.1; length of processus mandibularis (from caudal margin of condylus lateralis and cotyla quadratojugalis to rostral margin of condylus medialis), 62.6. Vertebra MHNT.PAL.2013.15.3: estimated length of arcus transversus at midline, 29.3; estimated length of dorsal part of corpus vertebrae at midline, 50.0. Vertebra MHNT.PAL.2013.15.5: width at processus transversi, 153.0; length of dorsal part of corpus vertebrae at midline, 59.2; width of facies articularis caudalis, 39.3; length from tip of zygapophysis caudalis to tip of zygapophysis cranialis, 91.5. Vertebra MHNT.PAL.2013.15.6: estimated height of facies articularis caudalis, 32.0; length from tip of zygapophysis caudalis to tip of zygapophysis cranialis, 83.0. Vertebra MHNT. PAL.2013.15.7: width at zygapophyses caudales, 85.4; length of arcus transversus at midline, 34.0; length of dorsal part of corpus vertebrae at midline, 47.1; width of facies articularis caudalis, 42.1; length from tip of zygapophysis caudalis to tip of zygapophysis cranialis, 63.0. Vertebra MHNT. PAL.2013.15.8: width at zygapophyses caudales, 74.8; length of arcus transversus at midline, 24.0; length of dorsal part of corpus vertebrae at midline, 39.1; width of facies articularis caudalis, 35.8. Femur MHNT.PAL.2013.15.9: length as preserved, 262.0; width of corpus femoris at mid-shaft, 49.6; depth of corpus femoris at mid-shaft, 38.4. Tibiotarsus MHNT.PAL.2013.15.10: length as preserved, 415.0; width of corpus tibiotarsi at mid-shaft, 38.3; depth of corpus tibiotarsi at mid-shaft, 25.1; length of crista fibularis, 107.0; depth of condylus lateralis, 55.2. Tibiotarsus APSO.2006. SP1-62: length as preserved, 430.0; width of corpus tibiotarsi at mid-shaft, 46.9; depth of corpus tibiotarsi at mid-shaft, 32.5; length of crista fibularis, 110.0; width of extremitas distalis, 93.0; depth of condylus lateralis, 60.1; depth of condylus medialis (estimated, due to imperfect preservation), 78.0. NB: measurements were not provided for vertebra MHNT. PAL.2013.15.4 because it is very badly preserved.

Description.—Maxilla:The maxilla (MHNT.PAL.2013.15.1) comes from site SP5 ( Laurent et al. 2010: fig. 2), along with a quadratum, vertebra cervicalis and tibiotarsus (see below). The maxilla is massive, tall and laterally compressed ( Fig. 1A View Fig ). It has a convex culmen about 2 cm thick, and lacks a hooked tip (hamulus rostri). MHNT.PAL.2013.15.1 is partly damaged at the tip and in the caudal part that lies sulcus nasi apertura nasi ossea in front of the orbita. The “maxillary socket” for the arcus jugalis found in Gastornis giganteus ( Cope, 1876) ( Fig. 1B View Fig ; Andors 1988) is not preserved. The lateral projection which contacts the os lacrimale is partially preserved on the right side ( Fig. 1A View Fig 2 View Fig ). The distance between the caudal rim of the apertura nasi ossea and the orbita was at least 2 cm. The apertura nasi ossea is in ventral position and its dorsal rim is located one-third the height from the lower border of the maxilla up to the culmen. A short furrow (sulcus nasi) extends in front of apertura nasi ossea on the lateral surface of the bill. Numerous grooves are found dorsal to the apertura nasi ossea. Some foramina neurovascularia are present on the distal part of the rostrum maxillae.

The maxilla from La Borie is similar to that of G. giganteus (AMNH6169) ( Fig. 1B View Fig ; Matthew and Granger 1917: pl. 20A, B), albeit slightly smaller. MHNT.PAL.2013.15.1 differs from G. giganteus in several features. The apertura nasi ossea is in more ventral position in Gastornis parisiensis Hébert, 1855 than in G. giganteus ( Fig. 1 View Fig ). In the latter species, the dorsal rim of the apertura nasi ossea is located at mid-height of the maxilla ( Fig. 1B View Fig ; Matthew and Granger 1917: pl. 20A, B). The portion located rostral to the apertura nasi ossea is proportionally shorter in the maxilla from la Borie than in G. giganteus . In MHNT.PAL.2013.15.1, the apertura nasi ossea is slightly larger and faces more laterally than in G. giganteus , and the sulcus nasi is shallower ( Fig. 1 View Fig ).

The maxilla R2583 from Cernay-lès-Reims ( Martin 1992: fig. 1) is too large to fit with the tarsometatarsus described as the type specimen of Gastornis russelli Martin, 1992 ( Martin 1992: fig. 6), but its size is much smaller than those of MHNT.PAL.2013.15.1 and AMNH6169. Some anatomical details suggest that this maxilla might belong to a juvenile individual of G. parisiensis : the contact between processus frontalis of os premaxillare and processus premaxillaris of os nasale is not fully ossified (open sutura) and is visible on the dorsal edge of the maxilla and on the ventral border of the pila supranasalis, which is not the case in adult individuals of Gastornis . The apertura nasi ossea is also very large with a relatively slender pila supranasalis, which is probably due to an incomplete ossification of the bones in this region.

Quadratum: The right os quadratum (MHNT.PAL.2013. 15.2) probably belongs to the same individual as the maxilla described above, because both fossils were found close to each other within the same layer, in site SP5. The os quadratum of Gastornis parisiensis is well preserved except the tip of the processus orbitalis and medial margin of the processus oticus ( Fig. 2A View Fig ). The quadratum is large and stout, with a well-developed processus orbitalis that is depressed on the medial side. The processus oticus has a single head with two distinct facets (condyli), and its curved rostral border is continuous with a large tuberculum musculi adductor mandibulae ossis quadrati (eminentia articularis) ( Fig. 2A View Fig 1 View Fig , A 2 View Fig ). The elongate processus mandibularis bears only two condyli ( Fig. 2A View Fig 4 View Fig ), and the cotyla quadratojugalis is shallow Fig. 2A View Fig 5 View Fig ).

Comparisons were made with: (i) a quadratum from the late Paleocene of Cernay-lès-Reims (R3561; Fig. 2C View Fig ) and two quadrata from the late Paleocene of Mont-de-Berru (BR617, which is represented in Fig. 2B View Fig , and BR12461) which also belong to G. parisiensis ( Martin 1992) ; (ii) the quadrata of Gastornis giganteus (AMNH6169). MHNT.PAL.2013.15.2 is comparable in size to R3561 and AMNH6169 and slightly larger than the two specimens from Berru.

G. parisiensis (MHNT.PAL.2013.15.2) differs from G. giganteus in the relatively more slender and pointed processus orbitalis ( Fig. 2A View Fig 1 View Fig ). In G. giganteus , this structure is extremely stout and truncated at the extremity ( Matthew and Granger 1917: pl. 22: 2a). The processus orbitalis is not preserved in the quadrata from Cernay and Berru assigned to G. parisiensis ( Fig. 2C View Fig ). In G. parisiensis , the condyli are aligned with each other, and the lateral edge of the processus mandibularis is convex ( Fig. 2A View Fig 4 View Fig ). In G. giganteus , the condylus medialis is more deflected medially with respect to the condylus lateralis and a distinct depression separates the two condyli ( Matthew and Granger 1917: pl. 22: 2c). The medial edge of the condylus medialis exhibits a process in MHNT.PAL.2013.15.2 ( Fig. 2A View Fig 3 View Fig ). This convexity is also present in the quadrata from Cernay and Berru, albeit less prominent, and absent in G. giganteus . In G. parisiensis , a sharp ridge delimits the condylus medialis rostrolaterally and extends medial to the condylus pterygoideus ( Fig. 2A 2 View Fig , A 3 View Fig ). This “rostral ridge” occurs in the quadrata from La Borie and Cernay/Berru. In G. giganteus , this ridge is absent.

MHNT.PAL.2013.15.2 exhibits features which are absent in the quadrata from the eastern Paris Basin (Cernay and Berru) and in the quadrata of G. giganteus : in MHNT.PAL.2013.15.2, the tuberculum musculi adductor mandibulae is oval in shape and continuous with a sharp curved ridge that constitutes the rostral border of the processus oticus ( Fig. 2A View Fig 1 View Fig , A 2 View Fig ). In the quadrata from Cernay and Berru, the tuberculum is very prominent and pointed, somewhat “hooked” ventrally ( Fig. 2B, C View Fig ). In G. giganteus , the tuberculum musculi adductor mandibulae is large and rounded ( Matthew and Granger 1917: pl. 22: 2a, b), and there is no ridge at the rostral edge of the processus oticus.Among the G. parisiensis specimens, differences occur between the quadratum from the early Eocene of La Borie and the quadrata from the late Paleocene of the eastern Paris Basin. In the quadratum from La Borie, the processus mandibularis is slender, lateromedially narrow, and the concavity that separates the two condyli is shallow ( Fig. 2A View Fig 4 View Fig ). In the quadrata from Cernay and Berru, the processus mandibularis is markedly wider and shorter, and the condyli are more convex and separated by a deeper depression ( Fig. 2B, C View Fig ). The cotyla quadratojugalis of MHNT.PAL.2013.15.2 is shallow ( Fig. 2A View Fig 1 View Fig , A 5 View Fig ), as in G. giganteus . In contrast, the cotyla quadratojugalis of the quadrata from Cernay and Berru is deep, circular, surrounded by a thick edge ( Fig. 2B, C View Fig ). Part of these differences might be due to preservation, since the specimen from La Borie appears lateromedially compressed compared to other examined Gastornis quadrata. Some of these differences probably reflect intraspecific variation within G. parisiensis , in addition to the fact that the specimens from the eastern Paris Basin and the specimen from La Borie are Thanetian and Ypresian in age, respectively.

Vertebrae cervicales: Vertebral remains include six vertebrae cervicales that are broken and/or crushed to various degrees. Four of them (MHNT.PAL.2013.15.3–6) were found in close proximity to one another and in the same layer, along with a left tibiotarsus (see below), in locus SP1. These vertebrae most probably come from the same individual. MHNT. PAL.2013.15.6 belongs to the cranial series (sectio I, facies articularis cranialis facing ventrally) ( Fig. 3A View Fig ), and the three other vertebrae (MHNT.PAL.2013.15.5 represented in Fig. 3D View Fig ) belong to the beginning of the intermediate series (sectio II, facies articularis cranialis facing dorsally). A vertebra cervicalis (MHNT.PAL.2013.15.8) of the intermediate series was found in site SP5, in close association with cranial remains (see above) and right tibiotarsus (see below). It is well preserved, undistorted, and lacks the left ansa costotransversaria ( Fig. 3C View Fig ). An isolated vertebra cervicalis (MHNT. PAL.2013.15.7) of the intermediate series was found in site SP2, at the bottom of the fossiliferous layer, along with turtle remains. It is well preserved, undistorted, and lacks part of the left ansa costotransversaria ( Fig. 3B View Fig ). This vertebra is slightly larger in size than other vertebral remains.

The vertebrae cervicales are heterocoelous, extremely massive and greatly shortened craniocaudally. The corpus vertebrae is short and wide. The zygapophyses are stout and their facies articulares are large, round and flat. The processus costales are short and blunt at the tip ( Fig. 3D View Fig 1 View Fig ). The cranial vertebra cervicalis exhibits a small foramen arcocostalis cranialis and its arcus vertebrae is longer than in intermediate vertebrae cervicales ( Fig. 3A View Fig ). The vertebrae cervicales of the intermediate series have stout processus transversi ( Fig. 3D View Fig 1 View Fig ) and very large foramina transversaria ( Fig. 3B 3 View Fig , C 2 View Fig ). The arcus vertebrae is very short craniocaudally and has marked area ligamenti elastici on either side ( Fig. 3B 3 View Fig ). The facies articularis cranialis is separated from the bottom of the corpus vertebrae by a deep ventral furrow ( Fig. 3D View Fig 1 View Fig ). Caudalmost vertebrae of the intermediate series (MHNT.PAL.2013.15.7 and MHNT.PAL.2013.15.8) exhibit well developed processus carotici and a deep sulcus caroticus ( Fig. 3B 3 View Fig , C 2 View Fig ). The facies articulares of the zygapophyses craniales and caudales are separated from each other by a very short distance ( Fig. 3B View Fig 2 View Fig ). The vertebrae cervicales from La Borie are exceedingly similar to the two vertebrae cervicales from Cernay-lès-Reims (listed in Martin 1992) and one vertebra cervicalis from Mont-de-Berru also deposited in the collections of the MNHN (BR 14568, not listed in Martin 1992). The vertebrae cervicales of Gastornis parisiensis closely resemble those preserved in Gastornis giganteus ( Matthew and Granger 1917: pls. 23–25).

Femur: The left femur (MHNT.PAL.2013.15.9) was found in site SP2, at the top of the fossiliferous layer, in contact with a gravel bar. This specimen does not preserve many diagnostic features. MHNT.PAL.2013.15.9 consists of the shaft, and the proximal and distal extremities are broken. On the facies cranialis, the distal end of the crista trochanteris is visible and continuous with an oblique linea intermuscularis cranialis. The facies caudalis ( Fig. 4A View Fig ) preserves an impressio musculi iliotrochantericus, most of the fossa poplitea, and a large, ovoid tuberculum musculi gastrocnemius pars zygapophysis caudalis zygapophysis torus dorsalis lateralis, which is located at the base of the condylus lateralis. The crista trochanteris extends far distally on the shaft. The latter is craniocaudally compressed and distinctly deflected medially towards the base of the condylus medialis. The fossa poplitea is deep and the tuberculum musculi gastrocnemius pars lateralis is an oval concavity. The femur MHNT. PAL.2013.15.9 possibly belongs to a juvenile individual, because it is smaller than the tibiotarsi described below. This is also supported by the fact that this specimen was found isolated from other Gastornis remains.

Tibiotarsi: The left tibiotarsus (MHNT.PAL.2013.15.10) was found associated with cranial remains and a vertebra, in site SP5. MHNT.PAL.2013.15.10 includes the base of the cristae cnemiales, the shaft, and a badly preserved extremitas distalis ( Fig. 4C View Fig ). The right tibiotarsus (APSO.2006. SP1-62) was found next to a series of vertebrae cervicales in site SP1. APSO.2006.SP1-62 includes an incomplete extremitas proximalis that only preserves the crista cnemialis lateralis, the slightly crushed shaft, and a well-preserved extremitas distalis ( Fig. 4B View Fig ). These specimens are from two different individuals because the left tibiotarsus is slightly smaller than the right one, and because they come from two different sites.

The cristae cnemiales are strongly deflected laterally, as in the Gastornis parisiensis tibiotarsus previously described from the same locality ( Buffetaut 2008: fig. 2). The crista cnemialis lateralis is proximally prominent and its thick lateral margin is slightly twisted caudally ( Fig. 4B View Fig 1 View Fig , B 2 View Fig ). The crista fibularis is thick and elongate ( Fig. 4B View Fig 1 View Fig , B 2 View Fig , C). The shaft is straight and craniocaudally compressed. Its lateral margin shows a slight concavity that corresponds to the foramen interosseum distale, just distal to the crista fibularis Fig. 4C View Fig ). The linea musculi fibularis is well marked and extends to the condylus lateralis. A drop-shaped impressio ligamenti collateralis medialis is located on the facies medialis of the shaft, level with the proximal end of the crista fibularis ( Fig. 4B View Fig 2 View Fig ). The linea extensoria extends from the distal end of the crista cnemialis cranialis down to the tuberositas retinaculi extensori located medial to the sulcus extensorius ( Fig. 4B View Fig 2 View Fig ). The extremitas distalis is curved medially Fig. 4B View Fig 3 View Fig ). The pons supratendineus is about 4 mm thick and 15 mm wide. It is oblique and located in the medial part of the tibiotarsus, its lateral margin being at the level of the midpoint of the shaft, as in the specimen previously described from La Borie ( Buffetaut 2008). The incisura intercondylaris is wide and bounded distally by a prominent ridge that joins the distal edges of the condyli. A similar ridge is clearly visible in the tibiotarsus of G. parisiensis ( Martin 1992: fig. 2), Gastornis giganteus ( Matthew and Granger 1917: pl. 32) and Gastornis xichuanensis ( Hou, 1980) (Buffetaut 2013: fig. 2a). The condylus medialis protrudes further cranially than the condylus lateralis ( Fig. 4B 4 View Fig ). The size and shape of the new tibiotarsi from La Borie match well with those of other specimens of G. parisiensis ( Martin 1992; Buffetaut 1997, 2008; and references therein).

Stratigraphic and geographic range.—Thanetian (Late Paleocene) to Ypresian (early Eocene); France (Meudon, Passy, Berru, Cernay, Saint-Papoul), England (Croydon), and Belgium (Mesvin).