[D] Lectavis bretincola [~/~]
Describer
Chiappe, 1993
Time
Cretaceous Late Campanian Maastrichtian
Classification
Saurischia Theropoda Tetanurae Coelurosauria Maniraptora Avialae Ornithothoraces Enantiornithes
Fossilsite
Lecho Formation, Estancia El Brete, Department of Candelaria, Province of Salta, Argentina
Info
Tarsometatarsus and tibiotarsus.
Enantiomithine bird with long and slender tibiotarsus and tarsometatarsus possessing the following autapomorphies: suboval articular surface of proximal end of tibiotarsus; distal tibiotarsal condyles strongly projected cranially; plantar surface ofproximal half of metatarsal II forming a prominent edge; subcircular knob on proximal end of metatarsal II; hypotarsus mostly developed over metatarsal II.
Etymology
Lectavis from Latin lectus, equivalent to the the Spanish word lecho (\\\"bed\\\"), in reference to the Lecho Formation, and avis, \\\"bird\\\"; bretincola from the combination of \\\"Brete\\\" and the Latin incola, which means \\\"an inhabitant.\\\"
Holotype
PVL-4021-1 (figs. 5, 6). Left tibiotarsus and incomplete tarsometatarsus, missing the distal end of the latter and most of metatarsal IV.
Description
The tibiotarsus of Lectavis bretincola is poorly preserved. It is long, slender, and craniocaudally compressed. The morphology of the proximal end differs with respect to the other El Brete enantiornithine tibiae (e. g., PVL-4032-1, PVL-4033, PVL-4036, PVL-4696), Concornis lacustris (Sanz and Buscalioni, 1992), and the Australian enantiornithine Nanantius eos (Molnar, 1986) in that in proximal view it is not circular but ellipsoidal, with a lateromedial major axis. The shaft is compressed craniocaudally. Distally, the condyles of the tibiotarsus of L. bretincola are strongly projected cranially, much more than in any other enantiomithine tibiotarsi from El Brete (e.g., PVL-4030, PVL-4033, PVL-4695) and in Nanantius eos. As in the remaining enantiomithines, the medial condyle is inflated, and considerably larger than the lateral one.
The intercondylar notch separating these condyles is less pronounced and broader than in the remaining El Brete tibiotarsi and in N. eos. Well-developed epicondylar fossae are present on the sides of the condyles. Lectavis bretincola possesses a long and slender tarsometatarsus. Metatarsals II-IV are strongly attached to each other over their length, and they are completely fused proximally. The fusion between metatarsals II and III starts more distally (approximately 24.7 mm from the proximal end) than does the fusion between metatarsals III and IV (approximately 17.3 mm from the proximal end). Dorsally, the tarsometatarsus of L. bretincola is in general flat, while in plantar view it is deeply excavated. This excavation is especially pronounced in the proximal portion, where metatarsal II forms a strong ridge that medially borders a depressed area formed by metatarsals III and IV.
In dorsal view metatarsal III is the broadest, narrowing smoothly distally. Its proximal portion is dorsoplantarly thin while distally it becomes thicker. Metatarsal II is the more conspicuous of the three. Its main axis is in the dorsoplantar plane, and plantarly it forms a prominent and robust ridge, which attenuates distally. In the most proximal portion, this ridge is continuous with a triangular-shaped hypotarsus. In contrast to the typical modem avian condition, the hypotarsus of Lectavis bretincola is mostly developed on the plantar surface of metatarsal II.
The medial surface of this metatarsal is basically flat, with only a slightly depressed central area in its most proximal portion. Dorsally, in the most proximal portion ofmetatarsal II, there is a prominent round tubercle. Above this tubercle, a nearly crescent-shaped fossa is located between metatarsals II and III. Metatarsal IV is badly preserved. It is significantly smaller than the remaining ones . Its proximal portion is remarkably thin.
On the basis of the groove left for its contact on the lateral border of metatarsal III, as with the latter, metatarsal IV became thicker toward the distal end. Both cotylae in the proximal articular surface are ovate in outline, and their major axes are oriented in a mediodorsallateroplantar direction. The medial cotyla is slightly larger than the lateral cotyla, and its dorsal border is more elevated as well. The plantar border of the medial cotyla, above the hypotarsus, is projected proximally. As was pointed out by Walker (1981), the hypotarsus has a subrectangular shape in proximal view, and lacks any crest or sulcus. The distal end of the tarsometata rsus of the single specimen of Lectavis bretincola is missing.
Chiappe, 1993
Time
Cretaceous Late Campanian Maastrichtian
Classification
Saurischia Theropoda Tetanurae Coelurosauria Maniraptora Avialae Ornithothoraces Enantiornithes
Fossilsite
Lecho Formation, Estancia El Brete, Department of Candelaria, Province of Salta, Argentina
Info
Tarsometatarsus and tibiotarsus.
Enantiomithine bird with long and slender tibiotarsus and tarsometatarsus possessing the following autapomorphies: suboval articular surface of proximal end of tibiotarsus; distal tibiotarsal condyles strongly projected cranially; plantar surface ofproximal half of metatarsal II forming a prominent edge; subcircular knob on proximal end of metatarsal II; hypotarsus mostly developed over metatarsal II.
Etymology
Lectavis from Latin lectus, equivalent to the the Spanish word lecho (\\\"bed\\\"), in reference to the Lecho Formation, and avis, \\\"bird\\\"; bretincola from the combination of \\\"Brete\\\" and the Latin incola, which means \\\"an inhabitant.\\\"
Holotype
PVL-4021-1 (figs. 5, 6). Left tibiotarsus and incomplete tarsometatarsus, missing the distal end of the latter and most of metatarsal IV.
Description
The tibiotarsus of Lectavis bretincola is poorly preserved. It is long, slender, and craniocaudally compressed. The morphology of the proximal end differs with respect to the other El Brete enantiornithine tibiae (e. g., PVL-4032-1, PVL-4033, PVL-4036, PVL-4696), Concornis lacustris (Sanz and Buscalioni, 1992), and the Australian enantiornithine Nanantius eos (Molnar, 1986) in that in proximal view it is not circular but ellipsoidal, with a lateromedial major axis. The shaft is compressed craniocaudally. Distally, the condyles of the tibiotarsus of L. bretincola are strongly projected cranially, much more than in any other enantiomithine tibiotarsi from El Brete (e.g., PVL-4030, PVL-4033, PVL-4695) and in Nanantius eos. As in the remaining enantiomithines, the medial condyle is inflated, and considerably larger than the lateral one.
The intercondylar notch separating these condyles is less pronounced and broader than in the remaining El Brete tibiotarsi and in N. eos. Well-developed epicondylar fossae are present on the sides of the condyles. Lectavis bretincola possesses a long and slender tarsometatarsus. Metatarsals II-IV are strongly attached to each other over their length, and they are completely fused proximally. The fusion between metatarsals II and III starts more distally (approximately 24.7 mm from the proximal end) than does the fusion between metatarsals III and IV (approximately 17.3 mm from the proximal end). Dorsally, the tarsometatarsus of L. bretincola is in general flat, while in plantar view it is deeply excavated. This excavation is especially pronounced in the proximal portion, where metatarsal II forms a strong ridge that medially borders a depressed area formed by metatarsals III and IV.
In dorsal view metatarsal III is the broadest, narrowing smoothly distally. Its proximal portion is dorsoplantarly thin while distally it becomes thicker. Metatarsal II is the more conspicuous of the three. Its main axis is in the dorsoplantar plane, and plantarly it forms a prominent and robust ridge, which attenuates distally. In the most proximal portion, this ridge is continuous with a triangular-shaped hypotarsus. In contrast to the typical modem avian condition, the hypotarsus of Lectavis bretincola is mostly developed on the plantar surface of metatarsal II.
The medial surface of this metatarsal is basically flat, with only a slightly depressed central area in its most proximal portion. Dorsally, in the most proximal portion ofmetatarsal II, there is a prominent round tubercle. Above this tubercle, a nearly crescent-shaped fossa is located between metatarsals II and III. Metatarsal IV is badly preserved. It is significantly smaller than the remaining ones . Its proximal portion is remarkably thin.
On the basis of the groove left for its contact on the lateral border of metatarsal III, as with the latter, metatarsal IV became thicker toward the distal end. Both cotylae in the proximal articular surface are ovate in outline, and their major axes are oriented in a mediodorsallateroplantar direction. The medial cotyla is slightly larger than the lateral cotyla, and its dorsal border is more elevated as well. The plantar border of the medial cotyla, above the hypotarsus, is projected proximally. As was pointed out by Walker (1981), the hypotarsus has a subrectangular shape in proximal view, and lacks any crest or sulcus. The distal end of the tarsometata rsus of the single specimen of Lectavis bretincola is missing.