Lecho Formation

The Lecho Formation is a geological formation in the Salta Basin of the provinces Jujuy and Salta of northwestern Argentina. Its strata date back to the Early Maastrichtian, and is a unit of the Salta Group. The fine-grained bioturbated sandstones of the formation were deposited in a fluvial to lacustrine coastal plain environment.

Dinosaur remains are among the fossils that have been recovered from the formation.[1]

According to Frankfurt and Chiappe (1999), the Lecho Formation is composed of reddish sandstones. The Lecho is part of the Upper/Late Cretaceous Balbuena Subgroup (Salta Group), which is a near-border stratigraphic unit of the Andean sedimentary basin. Fossils from this formation include the titanosaur Saltasaurus along with a variety of avian and non-avian theropods.

Lecho Formation
Stratigraphic range: Early Maastrichtian
~70–68 Ma
TypeGeological formation
Unit ofSalta Group
UnderliesYacoraite Formation
OverliesLos Blanquitos Formation
Lithology
PrimarySandstone
Location
Coordinates26°06′S 65°24′W / 26.1°S 65.4°WCoordinates: 26°06′S 65°24′W / 26.1°S 65.4°W
Approximate paleocoordinates28°36′S 52°00′W / 28.6°S 52.0°W
RegionJujuy, Salta
Country Argentina
ExtentSalta Basin
Lecho Formation is located in Argentina
Lecho Formation
Lecho Formation (Argentina)

Fossil content

See also

References

  1. ^ Weishampel, David B; et al. (2004). "Dinosaur distribution (Late Cretaceous, South America)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 600-604. ISBN 0-520-24209-2.
  2. ^ a b c d e Walker and Dyke (2009). "Euenantiornithine birds from the Late Cretaceous of El Brete (Argentina)." Irish Journal of Earth Sciences, 27: 15-62.
  3. ^ a b c d e f g h i j k l "63.7 Provincia de Salta, Argentina; 3. Lower Kirtland Formation," in Weishampel, et al. (2004). Page 603.
  4. ^ a b "Table 11.1," in Weishampel, et al. (2004). Page 213.
  5. ^ "Table 3.1," in Weishampel, et al. (2004). Page 49.
  6. ^ Frankfurt, N.G., and L.M. Chiappe (1999). "A Possible Oviraptorosaur From The Late Cretaceous of Northwestern Argentina," Journal of Vertebrate Paleontology, 19(1): 101-105.
  7. ^ Agnolin, F.L., and Martinelli, A.G. (2007) "Did oviraptorosaurs (Dinosauria; Theropoda) inhabit Argentina?" Cretaceous Research, 28: 785-790.
  8. ^ "Table 13.1," in Weishampel, et al. (2004). Page 270.
  9. ^ a b "Table 11.1," in Weishampel, et al. (2004). Page 214.

Bibliography

  • Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. 861 pp. ISBN 0-520-24209-2.
1980 in paleontology

Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 1980.

1993 in paleontology

Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 1993.

Allen Formation

The Allen Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous (middle Campanian to early Maastrichtian. Dinosaur remains are among the fossils that have been recovered from the formation.

Anacleto Formation

The Anacleto Formation is a geologic formation with outcrops in the Argentine Patagonian provinces of Mendoza, Río Negro, and Neuquén. It is the youngest formation within the Neuquén Group and belongs to the Río Colorado Subgroup. Formerly that subgroup was treated as a formation, and the Anacleto Formation was known as the Anacleto Member.The type locality of this formation lies 40 kilometres (25 mi) west of the city of Neuquén. At its base, the Anacleto Formation conformably overlies the Bajo de la Carpa Formation, also of the Río Colorado Subgroup, and it is in turn unconformably overlain by the Allen Formation of the younger Malargüe Group.The Anacleto Formation varies between 60 and 90 metres (200 and 300 ft) thick, and consists mainly of claystones and mudstones, purple

and dark red in color, deposited in fluvial, lacustrine and floodplain environments. Geodes are often found scattered throughout this formation.

Avisauridae

Avisauridae is a family of extinct enantiornithean birds from the Cretaceous period, distinguished by several features of their ankle bones. Depending on the definition used, Avisauridae is either a broad and widespread group of advanced enantiornitheans (following Cau & Arduini, 2008), or a small family within that group, restricted to species from the Late Cretaceous of North and South America (following Chiappe, 1992).

Avisaurus

Avisaurus (meaning "bird lizard") is a genus of enantiornithine bird from the Late Cretaceous of North America.

Elbretornis

Elbretornis is an extinct genus of enantiornithine which existed in what is now Salta Province, Argentina during the late Cretaceous period. It is known from the holotype PVL 4022, left humerus and associated right radius, ulna, scapula and coracoid, recovered from the El Brete locality (Maastrichtian age), Lecho Formation of Argentina. It was named by Cyril A. Walker and Gareth J. Dyke in 2009, and the type and so far only species is Elbretornis bonapartei. The generic name refers to the "El Brete" locality, where the fossil remains were found, and the Greek word for "bird" (ornis). The specific name honors José Bonaparte.As few elements are known from Elbretornis, it might actually belong to one of the El Brete enantiornithines known only from leg bones and described earlier, namely Lectavis, Soroavisaurus or Yungavolucris. However, Elbretornis was a smallish species, and the others were apparently all distinctly larger birds.

Enantiornis

Enantiornis is a genus of enantiornithine birds. The type and only currently accepted species E. leali is from the Late Cretaceous Lecho Formation at El Brete, Argentina. It was described from specimen PVL-4035, a coracoid, proximal scapula and proximal humerus found close to each other and suspected to represent the left shoulder of one individual bird.

Enantiornithes

Enantiornithes is a group of extinct avialans ("birds" in the broad sense), the most abundant and diverse group known from the Mesozoic era. Almost all retained teeth and clawed fingers on each wing, but otherwise looked much like modern birds externally. Over 80 species of enantiornitheans have been named, but some names represent only single bones, so it is likely that not all are valid. Enantiornitheans became extinct at the Cretaceous–Paleogene boundary, along with hesperornithids and all other non-avian dinosaurs. Enantiornitheans are thought to have left no living descendants.

Intiornis

Intiornis is an extinct genus of avisaurid enantiornithean birds which existed in what is now North-West Argentina during the late Cretaceous period (Campanian age). It is known from a partial hind limb found in beds of the Upper Cretaceous Las Curtiembres Formation. It was named by Fernando Emilio Novas, Federico Lisandro Agnolín and Carlos Agustín Scanferla in 2010, and the type species is Intiornis inexpectatus. Intiornis was the size of a sparrow, thus representing the smallest enantiornithes known from South America. Its closest relative was Soroavisaurus from the Lecho Formation (Maastrichtian age) of North-West Argentina.

Lectavis

Lectavis is a genus of enantiornithine birds. Their fossil bones have been recovered from the Late Cretaceous (Maastrichtian, c. 70.6 – 66 mya) Lecho Formation at estancia El Brete, Argentina. The genus contains a single species, Lectavis bretincola.

List of stratigraphic units with dinosaur body fossils

This is a list of stratigraphic units from which dinosaur body fossils have been recovered. Although Dinosauria is a clade which includes modern birds, this article covers only Mesozoic stratigraphic units. Units listed are all either formation rank or higher (e.g. group).

Martinavis

Martinavis is a genus of enantiornithine birds which existed in what is now southern France, North America and Salta Province, Argentina during the late Cretaceous period. It was named by Cyril A. Walker, Eric Buffetaut and Gareth J. Dyke in 2007, and the type species is Martinavis cruzyensis.

M. cruzyensis is known from the holotype ACAP-M 1957, a complete uncrushed right humerus, recovered from the Massecaps locality, Cruzy, which is in a Campanian/Maastrichtian-stage deposits in the Grès à Reptiles Formation of France.

A second species, M. vincei is known from the holotype PVL 4054, a complete left humerus and from the associated paratype PVL 4059, a distal end of left humerus, recovered from the El Brete locality (Maastrichtian age), Lecho Formation of Argentina.

A possible third species is represented by the unnamed specimen KU-NM-37 from United States.In 2009, three additional species were named from the same location as M. vincei:

M. minor is known from the holotype PVL 4046, a distally imperfect right humerus

M. saltariensis is known from the holotype PVL 4025, an incomplete left humerus, lacking the median ridge

M. whetstonei is known from the holotype PVL 4028, a distally imperfect left humerusM. vincei is the largest of the El Brete taxa, approaching its huge (by enantiornithine standards), sympatric and coeval Enantiornis in size. M. saltariensis is somewhat smaller. M. minor is notably smaller than the former two, while M. whetstonei was a diminutive version of M. vincei, being at most half its size. In addition to size, the species differ slightly in proportions and qualitative features, making it unlikely the represent sexual or age variation.As few elements are known from El Brete Martinavis, it might be the same species as one of the other enantiornithines of that locality which were described earlier based on from leg bones. While the tarsometatarsus of Yungavolucris seems too wide (and short) to match Martinavis, and Lectavis was slightly larger (and its tibiotarsus differs from one tentatively assigned to Martinavis), the Soroavisaurus tarsometatarsus is about the size expected for M. vincei and perhaps M. saltariensis. These differ slightly in size but also in proportions, meaning M. saltariensis, while generally smaller, might nonetheless have had thicker legs, and thus match Soroavisaurus.

Noasaurus

Noasaurus ("Northwestern Argentina lizard") is a genus of ceratosaurian theropod dinosaur genus from the late Campanian-Maastrichtian (Late Cretaceous) of Argentina. The type and only species is N. leali.

Oviraptorosauria

Oviraptorosaurs ("egg thief lizards") are a group of feathered maniraptoran dinosaurs from the Cretaceous Period of what are now Asia and North America, though they have also been reported from the Eumeralla Formation of Australia and Lecho Formation in South America. They are distinct for their characteristically short, beaked, parrot-like skulls, with or without bony crests atop the head. They ranged in size from Caudipteryx, which was the size of a turkey, to the 8-metre-long, 1.4-ton Gigantoraptor. The group (along with all maniraptoran dinosaurs) is close to the ancestry of birds. Analyses like those of Maryanska et al (2002) and Osmólska et al. (2004) suggest that they may represent primitive flightless birds. The most complete oviraptorosaur specimens have been found in Asia. The North American oviraptorosaur record is sparse.The earliest and most basal ("primitive") known oviraptorosaurs are Ningyuansaurus wangi, Protarchaeopteryx robusta and Incisivosaurus gauthieri, both from the lower Yixian Formation of China, dating to about 125 million years ago during the Aptian age of the early Cretaceous period. A tiny neck vertebra reported from the Wadhurst Clay Formation of England shares some features in common with oviraptorosaurs, and may represent an earlier occurrence of this group (at about 140 million years ago).

Salta Basin

Salta Basin or Salta Rift Basin is a sedimentary basin located in the Argentine Northwest. The basin started to accumulate sediments in the Early Cretaceous (Neocomian) and at present it has sedimentary deposits reaching thicknesses of 5,000 metres (16,000 ft). The basin contains seven sub-basins: Tres Cruces, Lomas de Olmedo, Metán, Alemanía, Salfity, El Rey, Sey and Brealito. The basin environment has variously been described as a "foreland rift" and an "intra-continental rift". The basin developed under conditions of extensional tectonics and rift-associated volcanism.

Saltasaurus

Saltasaurus (which means "lizard from Salta") is a genus of titanosaurid sauropod dinosaur of the Late Cretaceous Period of Argentina. Small among sauropods, though still heavy by the standards of modern creatures, Saltasaurus was characterized by a short neck and stubby limbs. It was the first genus of sauropod known to possess armour of bony plates embedded in its skin. Such small bony plates, called osteoderms, have since been found on other titanosaurids.

Soroavisaurus

Soroavisaurus is a genus of enantiornithine birds related to Avisaurus. It lived during the Late Cretaceous of Argentina. The only known species, S. australis, is known from fossils collected from the Lecho Formation (Maastrichtian age) of Estancia El Brete, in the southern tip of the province of Salta, Argentina. The specimens are in the collection of the Fundación-Instituto Miguel Lillo, Tucumán. They are cataloged as PVL-4690, a 46.9 mm — long left tarsometatarsus, and PVL-4048, which includes another left tarsometatarsus, 51.5mm long and associated with the whole hallux, or digit I, and four intermediate phalanges. PVL-4048 was previously described as "Avisaurus sp." (see Avisaurus).

Yungavolucris

Yungavolucris is a genus of enantiornithean birds. It contains the single species Yungavolucris brevipedalis, which lived in the Late Cretaceous (Maastrichtian, c.70.6 – 66 mya). The fossil bones were found in the Lecho Formation at estancia El Brete, Argentina."Yungavolucris brevipedalis" means "Short-footed Yungas bird". The generic name, Yungavolucris is after the Yungas region + the Latin volucris, which translates to "bird" (literally "flyer"). The specific name brevipedalis is from the Latin brevis, which means "short", + pedalis, from the Latin pes, meaning "foot".

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