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==Discovery and naming==
==Discovery and naming==
The first [[fossil]]s of ''Langstonia'' were discovered in the province of Huila in Colombia by [[José Royo y Gomez]], during the expeditions in the region by the [[United States|American]] [[paleontologist]] [[Robert Stirton]]. They were found in the area called the Tatacoa Desert at the locality V-4517, characterized by gray [[claystone]] overlying [[sandstone]] sediments. These have been named the [[Honda Group]], of the La Venta fauna, the [[geological formation]] named the "lechos de momos" (Monkey Beds) in 1945.<ref name="langston1965"/>
The first [[fossil]]s of ''Langstonia'' were discovered in the province of Huila in Colombia by [[José Royo y Gomez]], during the expeditions in the region by the [[United States|American]] [[paleontologist]] [[Robert Stirton]]. They were found in the area called the Tatacoa Desert at the locality V-4517, characterized by gray [[claystone]] overlying [[sandstone]] sediments. These have been named the [[Honda Group]], of the La Venta fauna, the [[geological formation]] named the "lechos de momos" (Monkey Beds) in 1945.<ref name="langston1965"/> Many of the remains discovered would then be sent to the collections of the Museum of Paleontology at the [[University of California, Berkeley]] (UCMP, for its acronym in English), where they are still preserved. The description of the specimens sebécido not come until 1965, when the US [[Wann Langston Jr.]] published his monograph '' Fossil Crocodylians from Colombia '' ("fossil crocodilians in Colombia"), in which he made a detailed analysis of several fossils of this group in Colombia, including the remains of other species as '' [[Purussaurus | Purussaurus neivensis]]'' ''[[Mourasuchus|Mourasuchus atopus]]'' ''[[Gryposuchus|Gryposuchus colombianus]]'' and ''[[Charactosuchus|Charactosuchus fieldsi]]'' (plus a possible [[dyrosaurid]]) <ref>Langston 1965, p.6</ref> As for the sebecid material he choose as the [[holotype]] of a new species a bone fragment [[dental]], the UCMP 37877 specimen, which he called ''[[Sebecus]] huilensis''; <ref>Langston 1965, p.14</ref> thus extends the time range of this genus and the family, hitherto known only remains of [[Eocene]] of [[Argentina]]. Langston gives a new species remains considering that besides being larger, the dentary fragment is 68% larger than the Argentine species, ''S. icaeorhinus'' and proportionally thinner, with more recurved teeth and laterally compressed.<ref>Langston 1965, p.14</ref> Additionally Langston refers a series of zyphodont teeth in the area found this species, with some teeth referred to as similar but classified generally to ''Sebecus'' sp., which do not come from the Miocene but the [[Eocene]], found in the [[department of Santander]] in Colombia.<ref>Langston 1965, p.16</ref>

Subsequently Buffetaut and Hofferster (1977) reported from the Ipururo Formation in the Amazon region of [[Peru]] the presence of a huge cranial portion (area of the snout) to this species; although its age coincides with ''S. huilensis'' is distinguished by its larger and more robust proportions <ref>Buffetaut and Hoffstetter, 1977; Figure 1; p. 1664</ref>

Busbey (1986) later would bring new remains of the species also from the "Monkey Beds" of Huila in Colombia, this time a fragment of [[premaxilla]], smaller than '' S. icaeorhinus '', and equally thin; also described the first remains of the [[jugal]] bone, the suspensory and retroarticular joint in the jaw, and a fragment of bone scute ([[osteoderm]]), which were the earliest known for this family. <ref>Busbey 1968, p. 20</ref> Busbey also rule out that the Peruvian fossil belonging to ''S. huilensis ', based on its unique anatomy, less spaced teeth and a wider nose.<ref>Busbey 1986, p. 26.</ref>

Langston, along with the Argentine paleontologist Zulma Gasparini, reported new remains of the species in a contribution on fossil crocodylomorphs of Colombia for the book ''Vertebrate Paleontology of the Neotropics: The Miocene Fauna of La Venta'' (1997). In this case it would be new specimens of teeth, a somewhat fuller premaxilla, a previous fragment of tooth, and two [[vertebra]]e: above a sacral and a [[caudal]], which also were unknown to this group. The specimens discovered on this occasion were deposited in the Geological Museum of [[Ingeominas]] (previous name of Colombian Geological Service).<ref>Langston and Gasparini 1997, p.114</ref>

Moreover, the Paolillo and Jimenez (2007) described a new genus of a large Venezuelan Miocene sebecid, ''[[Barinasuchus]]'' of [[Venezuela]]. In their article they considered that the traits of two species of ''Sebecus'', ''S. huilensis'' and ''S. querejazus'' of [[Paleocene]] of [[Bolivia]] in addition to their age justify the creation of separate genres for both: the Colombian species is given the name ''Langstonia'', in honor of his initial descriptor and its "(..)advances in knowledge of crocodylians of Tertiary Colombia in particular and South America in general,"<ref>Paolillo and Jimenez 2007, p. 11.</ref> while ''S. querejazus'' is renamed ''[[Zulmasuchus]]'', although some authors (Pol 2011, Pol 2012, Carvalho ''et al.'' 2010 <ref>Carvalho ''et al.'' 2010, p . 38</ref>) still maintain both species within ''Sebecus''. Paolillo and Jimenez also clarified the status of the Peruvian fossil before assigned to the species, assigning it to ''Barinasuchus'', although it should be noted that this does not rule out its presence in more southern areas; in the area of the Peruvian Amazon known as the Fitzcarrald Arch has been found a characteristically flattened tooth from the middle Miocene therefore assigned to ''Langstonia''.<ref> Salas-Gismondi, p. 356.</ref>

Finally, a fossil of a premaxilla and maxilla fragment found in Itaboraí Basin in Brazil dating from the Middle Paleocene (and where have been found fossils of other sebecids) has been classified as related to this species, under the name of ''Sebecus'' cf. ''huilensis'', whose main features are very similar to ''Langstonia'', suggesting that the latter is part of a lineage of sebecids with an extensive temporal and geographical record. <ref>Pinheiro ''et al''. 2011b, p. R92</ref>

==Specimens known==

Here is a list of specimens assigned to the species, with a brief description of these. They are grouped according to the institution in which they are preserved:

=== Museum of Paleontology at the University of California ===
Not all materials from this collection were assigned to '' Langstonia huilensis '' but are included because of their similar morphology.
* '''UCMP 37877''': The front part of a right dentary preserving the mandibular [[symphysis]], with six tooth sockets of which five have broken teeth, collected in 1945 in the locality V-4517. This element measures 189.0 millimeters in length, being 68% higher than the rate of ''Sebecus icaeorhinus'' specimen. Their teeth are quite compressed and has a first side facing forward tooth, the second is directed upwards and the third also slopes, while others are vertical; the first teeth have a wide separation between them (diastema). Symphysis extending beyond the sixth tooth, while the bone surface is smoother than in ''S. icaeorhinus''.<ref>Langston 1965, p. 15-16</ref>
* '''UCMP 41308''': Base of a tooth of the Upper Eocene, from the V-4620 town (Tama fauna, [[department of Santander]], Mugrosa Formation). It measures 14.2 millimeters in diameter at the base.<ref>Langston 1965, p. 17</ref>
* '''UCMP 44562''': Tooth of the Late Oligocene fauna found in Coyaima, locality V-4411. It measures 22.5 mm. height at the crown.
* '''UCMP 40186''': A elongated, slender and compressed laterally tooth, with a slight curvature, intermediate in size between 44561 and other teeth reported, with larger saws (3 per millimeter tooth; in ''Langstonia'' typically are 4 to 6 mm).
* '''UCMP 40220''': A large tooth, locality V.4523, measures about 42.4 mm height.<ref>Langston 1965, p.17</ref>
* '''UCMP 44563''': A fragment of the dental crown, found in the locality V-4528; it measured 16.3 mm at the base of the crown.<ref>Langston 1965, p.17</ref>
* '''UCMP 44561''': The largest fragment dental crown reported of La Venta, locality V-4528. Reaches up to 20.5 mm. high, but its base is much wider than other teeth, reaching 23.8 mm. Apart from its size, three times that of the teeth of the holotype of the species, this tooth is characterized by a blunt, relatively straight edges and a more oval profile tranverasal fastened with small saws. It may not correspond to ''Langstonia''.<ref>Langston 1965, p.16</ref>
* '' 'UCMP 44566' '': The lower teeth reported by Langston (1965). Recovered in the locality V-4421, measuring just 6.1 mm. wide at the base.<ref>Langston 1965, p.17</ref>

=== Texas Memorial Museum (TMM) ===
* '''TMM 41658-8''': Includes a portion of the left anterior premaxillary, middle left maxillary fragment, a fragment of the left splenial bone, back of the left suspensory bone formed by parts of the quadratojugal, the [[square]] bone, opisthotic and a [[squamosal]], a left part of a [[jugal]], the left retroarticular processes (partial) right to the jaw and a fragment of a [[osteoderm]]. These fragments were recovered in 1976 in the "Monkey Pod" locality of La Venta (Baraya Member of the Villavieja Formation) by dr. Lundelius Ernest Jr.<ref>Busbey 1986, p. 20</ref>

===Museum of Geology, [[Ingeominas|Colombian Geological Survey]] (IGM)===
* '''IGM 250816''': Found in the Duke 57 locality in Villavieja Formation; consists of a right [[premaxilla]] and part of the [[maxilla]], the front left tooth, part of the dorsal border of a rostrum and two vertebrae. The premaxillary measured 12.8 cm in length, is tall and thin compared to the ''S. icaeorhinus'' being covered with fine grooves on its outer surface. It has three [[dental alveolus|dental alveoli]] in the premaxilla, from the edge of the second tooth to the fourth, which is particularly enlarged, being twice the third (reverse that in ''S. icaeorhinus''), while the first two teeth should be small.<ref>Langston and Gasparini 1997, p.114</ref> After the fourth premaxillary tooth there is a space or [[diastema]] in that fitted the fourth lower tooth that exceeded the 3.5 centimeters; has a narrow palate, lateral nasal aperture and without mild depression around.<ref>Langston and Gasparini 1997, p.115</ref> The dentary is high, with four sockets, two projecting forward and a third and fourth straight, the latter being the largest. The associated vertebrae are an amphycoelian sacral with a [[Sacrum|sacral]] rib attached, with a wide, rectangular neural spine; it measured 10.7 cm high by 5.5 cm wide, while it is estimated that the sacral ribs should be 10 cm wide at its rear end. The other is an anterior caudal vertebrae, perhaps the first, with incomplete neural spine, with a broad neural canal, and measures 2.8 cm wide and 2.1 high. <ref>Langston and Gasparini 1997, p.116</ref>
* '''IGM 184 427''': A tooth found in the Duke 91 locality. The crown of this is twice as high as it is wide, reaching 36 mm. high and 17 wide.<ref>Langston and Gasparini 1997, p.116</ref>
* '''IGM 250 541''': Tooth from the Duke 196 locality, is incomplete and worn, but is similar to the tooth UCMP 40186. It measures 39 mm high by 27 wide.<ref>Langston and Gasparini 1997, p. 116-117</ref>
* '''IGM 250 427''': A tooth of the Duke 106 locality. It is also incomplete, but your measurements (52 mm high by 30 mm wide) makes it the largest tooth reported for a sebecosuchian in Colombia.<ref>Langston and Gasparini 1997, p.116-117</ref>
* '''IGM 184378''': Tooth from Duke 40 locality. It measures 30 mm high by 17 wide.<ref>Langston and Gasparini 1997, p.117</ref>
* '''IGM 184 165''': A tooth of the Duke 41 locality, that probably correspond to a first [[maxilla]]r right tooth, measures 20 mm in height at the crown and 12 on the base, while its root has a length equivalent to 2.5 times the height of the crown. Unlike other teeth of ''L. huilensis'', has a slight groove at the base of the tooth crown, on the inner side thereof. <ref>Langston and Gasparini 1997, p.117</ref>

=== Department of Vertebrate Paleontology, Museum of Natural History, National University of San Marcos ===

* '''MUSM 912''': A single tooth found in the area of Fitzcarrald Arch in the localities of Inuya and Mapuya in the Amazon region of Peru; its size and shape are indistinguishable from 'L. huilensis ''.<ref>Salas-Gismondi, p. 356.</ref>

=== Museu de Ciências da Terra, Rio de Janeiro ===
* '''MCT 1795-R/1796-R''': consists of material of sebecid found in Itaboraí Basin in the state of Rio de Janeiro in Brazil. Includes a full left premaxilla with a tooth preserved, and a piece of left maxilla with two alveoli. By having very flattened and spaced teeth looks remarkably smilar to ''Langstonia'', being provisionally classified as ''Sebecus'' cf. ''huilensis''.<ref>Pinheiro' 'et al'., 2011, p. R92.</ref>

==Paleobiology==

Due to the fragmentary remains generally known for this family, its possible only describe some general aspects of the appearance and biology of ''Langstonia''. As mentioned above, the fossil type of the species is larger than ''Sebecus icaeorhinus'' with jaws and teeth even more flattened, although its general proportions are reminiscent of this species, which suggests that their skull would be higher and laterally flattened, in contrast to modern crocodilians, which generally have a horizontally flattened skull with conical teeth. Teeth are of the zyphodont kind, with very flattened sides, slightly curved back and with serrated edges with small denticles (between 5-6 denticles per milimeter in the teeth of this genus) and also without any grooves on its surface. This type of teeth appears in the close relatives of sebecids, the [[peirosaurid]]s and [[baurusuchid]]s of the [[Cretaceous]] and some [[crocodilian]]s of the [[Cenozoic]] as the [[pristichampsidae|pristichampsid]]s and some [[mekosuchine]]s. These forms were land animals that used their teeth to cut and tear their prey, because the traditional method of capture of the [[crocodile]]s, using its pressure force to retain and drown his victims is not viable on land; these crocodylomorphs also had more elongated limbs, stiff back, ideal to hold the weight and give strength to run. Langston had already suggested that these teeth were indicative that, this animal had more terrestrial habits than those of existing species and the Miocene contemporary crocodylians, and in the modern world only could be vaguely compared with the less aquatic habits of the caimans of the genus ''[[Paleosuchus]]'', which have a higher muzzle and a higher degree of ossification around the eye socket, so that the partially resemble sebecids.<ref>Langston 1965, p.134-135</ref> Busbey suggested the fact that his skull was high implied that these animals seek no make pressure during the bite indefinitely, but to produce cuts then back quickly so that the bleeding weaken their prey slowly up to devour, similar to the current [[Komodo dragon]], thereby adopting a strategy of stalking in areas where prey transiting frequently.<ref>Busbey 1986, p. 27</ref>

In the fauna of La Venta is noted that although there were some large mammalian predators (belonging to the group of [[Sparassodonta|sparassodont]]s, as ''[[Lycopsis|Lycopsis longirostrus]]'' and ''[[Dukecynus]]'') any of the known equated in size to contemporary crocodylomorphs, including ''Langtonia''<ref>Argot 2004a, p. 513</ref> and given the absence of large predatory birds [[Phorusrhacidae|phorusrhacids]] as in the southern part of the continent, these sebecids should be the terrestrial [[apex predator]]s in its ecosystem. The fossils found of other species - big fishes, manatees, large browsing [[meridiungulata|meridiungulates]] as ''[[Granastrapotherium]]'' and ''[[Huilatherium]]'', and some grazers as ''[[Pericotoxodon]]'' - indicate that the climate was warm and humid with heavy rainfall and with droughts periods no extending beyond 3-4 months, consisting of watersheds, forests and certain adjacent areas of open grasslands where it could hunt down a large variety of [[megafauna]].<ref>Kay and Madden, p. 534-535</ref>

The disappearance of the system of large rivers of the Amazon lake system and the gradual uplift of the [[Andes]] caused major ecological changes in South America in the mid-Miocene. Last sebecids, as ''Langstonia'' and ''Barinasuchus'' as apex predators in their environment, should be particularly susceptible to ecological changes that disappeared other lineages, particularly hoofed mammals (such as groups [[Astrapotheria]], [[Leontiniidae]], [[Adianthidae]] and [[Notohippidae]]), thus leading to extinction to the last notosuchians crocodilomorphs of the world.<ref>Riff ''et al.'' 2011, p. 29</ref><ref>Prevosti ''et al.'' 2013, p. 20 </ref>

==Phylogeny==

''Langstonia'' is considered part of [[Sebecosuchia]] zifodontes lineage crocodilomorphs land forming part of a separate lineage of ancient southern continent of [[Gondwana]]. As noted earlier, this species formerly part of the genus ''Sebecus'' and [[phylogeny|phylogenetic analyzes]] have consistently shown that these forms a clade within Sebecidae next to ''S. icaeorhinus'' and ''Zulmasuchus'', not so closely related to ''Barinasuchus'' and ''[[Bretesuchus]]''. [[Cladogram]] based on Pol and Powell, 2011: <ref>Pol and Powell, 2011</ref>

{{clade | style = font-size: 85%; line-height: 85%
| 1 = {{clade
| 1 = {{clade
| 1 = ''[[Chimaerasuchus]]''
| 2 = ''[[Sphagesaurus]]''}}
| label2 = '''Sebecosuchia'''
| 2 = {{clade
| 1 = ''[[Pehuenchesuchus]]''
| 2 = {{clade
| 1 = ''[[Cynodontosuchus]]''
| label2 = [[Baurusuchidae]]
| 2 = {{clade
| 1 = {{clade
| 1 = ''[[Pabwehshi]]''
| 2 = ''[[Stratiotosuchus]]''}}
| 2 = {{clade
| 1 = '' [[Baurusuchus|Baurusuchus pachecoi]] ''
| 2 = ''[[Baurusuchus|Baurusuchus salgadoensis]]''}}}}
| 3 = {{clade
| label1 = [[Bergisuchidae]]
| 1 = ''[[Bergisuchus]]''
| label2 = [[Iberosuchidae]]
| 2 = ''[[Iberosuchus]]''
| label3 = [[Sebecidae]]
| 3 = {{clade
| 1 = ''[[Lorosuchus]]''
| 2 = {{clade
| 1 = ''[[Barinasuchus]]''
| 2 = {{clade
| 1 = {{clade
| 1 = ''[[Ayllusuchus]]''
| 2 = ''[[Bretesuchus]]''}}
| 2 = {{clade
| 1 = Form of Lumbrera
| 2 = '''''Langstonia'''''
| 3 = ''[[Sebecus]]''
| 4 = ''[[Zulmasuchus]]''}}}}}}}}}}}}}}}}}}

== References ==

=== Notes ===
{{reflist}}


==References==
==References==

Revision as of 07:49, 3 December 2014

Langstonia
Temporal range: Middle Miocene, 13–12 Ma
↓
Skeleton restoration
Restoration showing known elements, with remaining material filled in after related species
Scientific classification Edit this classification
Missing taxonomy template (fix): Langtonia
Species:
Template:Taxonomy/LangtoniaL. huilensis
Binomial name
Template:Taxonomy/LangtoniaLangtonia huilensis
(Langston, 1965)
Synonyms

Langstonia (meaning "[crocodile] of Langston", in honor of paleontologist Wann Langston, Jr.) is an extinct genus of notosuchian crocodylomorph of the family Sebecidae. It lived in the middle Miocene (specifically in the Laventan land-mammal age), in the "Monkey Beds" of the Colombian Villavieja Formation. Langstonia was named in 2007 by Alfredo Paolillo and Omar Linares for fossils originally described by Langston in 1965 as Sebecus huilensis. Thus, the type species is L. huilensis.[1]

Discovery and naming

The first fossils of Langstonia were discovered in the province of Huila in Colombia by José Royo y Gomez, during the expeditions in the region by the American paleontologist Robert Stirton. They were found in the area called the Tatacoa Desert at the locality V-4517, characterized by gray claystone overlying sandstone sediments. These have been named the Honda Group, of the La Venta fauna, the geological formation named the "lechos de momos" (Monkey Beds) in 1945.[2] Many of the remains discovered would then be sent to the collections of the Museum of Paleontology at the University of California, Berkeley (UCMP, for its acronym in English), where they are still preserved. The description of the specimens sebécido not come until 1965, when the US Wann Langston Jr. published his monograph Fossil Crocodylians from Colombia ("fossil crocodilians in Colombia"), in which he made a detailed analysis of several fossils of this group in Colombia, including the remains of other species as Purussaurus neivensis Mourasuchus atopus Gryposuchus colombianus and Charactosuchus fieldsi (plus a possible dyrosaurid) [3] As for the sebecid material he choose as the holotype of a new species a bone fragment dental, the UCMP 37877 specimen, which he called Sebecus huilensis; [4] thus extends the time range of this genus and the family, hitherto known only remains of Eocene of Argentina. Langston gives a new species remains considering that besides being larger, the dentary fragment is 68% larger than the Argentine species, S. icaeorhinus and proportionally thinner, with more recurved teeth and laterally compressed.[5] Additionally Langston refers a series of zyphodont teeth in the area found this species, with some teeth referred to as similar but classified generally to Sebecus sp., which do not come from the Miocene but the Eocene, found in the department of Santander in Colombia.[6]

Subsequently Buffetaut and Hofferster (1977) reported from the Ipururo Formation in the Amazon region of Peru the presence of a huge cranial portion (area of the snout) to this species; although its age coincides with S. huilensis is distinguished by its larger and more robust proportions [7]

Busbey (1986) later would bring new remains of the species also from the "Monkey Beds" of Huila in Colombia, this time a fragment of premaxilla, smaller than S. icaeorhinus , and equally thin; also described the first remains of the jugal bone, the suspensory and retroarticular joint in the jaw, and a fragment of bone scute (osteoderm), which were the earliest known for this family. [8] Busbey also rule out that the Peruvian fossil belonging to S. huilensis ', based on its unique anatomy, less spaced teeth and a wider nose.[9]

Langston, along with the Argentine paleontologist Zulma Gasparini, reported new remains of the species in a contribution on fossil crocodylomorphs of Colombia for the book Vertebrate Paleontology of the Neotropics: The Miocene Fauna of La Venta (1997). In this case it would be new specimens of teeth, a somewhat fuller premaxilla, a previous fragment of tooth, and two vertebrae: above a sacral and a caudal, which also were unknown to this group. The specimens discovered on this occasion were deposited in the Geological Museum of Ingeominas (previous name of Colombian Geological Service).[10]

Moreover, the Paolillo and Jimenez (2007) described a new genus of a large Venezuelan Miocene sebecid, Barinasuchus of Venezuela. In their article they considered that the traits of two species of Sebecus, S. huilensis and S. querejazus of Paleocene of Bolivia in addition to their age justify the creation of separate genres for both: the Colombian species is given the name Langstonia, in honor of his initial descriptor and its "(..)advances in knowledge of crocodylians of Tertiary Colombia in particular and South America in general,"[11] while S. querejazus is renamed Zulmasuchus, although some authors (Pol 2011, Pol 2012, Carvalho et al. 2010 [12]) still maintain both species within Sebecus. Paolillo and Jimenez also clarified the status of the Peruvian fossil before assigned to the species, assigning it to Barinasuchus, although it should be noted that this does not rule out its presence in more southern areas; in the area of the Peruvian Amazon known as the Fitzcarrald Arch has been found a characteristically flattened tooth from the middle Miocene therefore assigned to Langstonia.[13]

Finally, a fossil of a premaxilla and maxilla fragment found in Itaboraí Basin in Brazil dating from the Middle Paleocene (and where have been found fossils of other sebecids) has been classified as related to this species, under the name of Sebecus cf. huilensis, whose main features are very similar to Langstonia, suggesting that the latter is part of a lineage of sebecids with an extensive temporal and geographical record. [14]

Specimens known

Here is a list of specimens assigned to the species, with a brief description of these. They are grouped according to the institution in which they are preserved:

Museum of Paleontology at the University of California

Not all materials from this collection were assigned to Langstonia huilensis but are included because of their similar morphology.

  • UCMP 37877: The front part of a right dentary preserving the mandibular symphysis, with six tooth sockets of which five have broken teeth, collected in 1945 in the locality V-4517. This element measures 189.0 millimeters in length, being 68% higher than the rate of Sebecus icaeorhinus specimen. Their teeth are quite compressed and has a first side facing forward tooth, the second is directed upwards and the third also slopes, while others are vertical; the first teeth have a wide separation between them (diastema). Symphysis extending beyond the sixth tooth, while the bone surface is smoother than in S. icaeorhinus.[15]
  • UCMP 41308: Base of a tooth of the Upper Eocene, from the V-4620 town (Tama fauna, department of Santander, Mugrosa Formation). It measures 14.2 millimeters in diameter at the base.[16]
  • UCMP 44562: Tooth of the Late Oligocene fauna found in Coyaima, locality V-4411. It measures 22.5 mm. height at the crown.
  • UCMP 40186: A elongated, slender and compressed laterally tooth, with a slight curvature, intermediate in size between 44561 and other teeth reported, with larger saws (3 per millimeter tooth; in Langstonia typically are 4 to 6 mm).
  • UCMP 40220: A large tooth, locality V.4523, measures about 42.4 mm height.[17]
  • UCMP 44563: A fragment of the dental crown, found in the locality V-4528; it measured 16.3 mm at the base of the crown.[18]
  • UCMP 44561: The largest fragment dental crown reported of La Venta, locality V-4528. Reaches up to 20.5 mm. high, but its base is much wider than other teeth, reaching 23.8 mm. Apart from its size, three times that of the teeth of the holotype of the species, this tooth is characterized by a blunt, relatively straight edges and a more oval profile tranverasal fastened with small saws. It may not correspond to Langstonia.[19]
  • 'UCMP 44566' : The lower teeth reported by Langston (1965). Recovered in the locality V-4421, measuring just 6.1 mm. wide at the base.[20]

Texas Memorial Museum (TMM)

  • TMM 41658-8: Includes a portion of the left anterior premaxillary, middle left maxillary fragment, a fragment of the left splenial bone, back of the left suspensory bone formed by parts of the quadratojugal, the square bone, opisthotic and a squamosal, a left part of a jugal, the left retroarticular processes (partial) right to the jaw and a fragment of a osteoderm. These fragments were recovered in 1976 in the "Monkey Pod" locality of La Venta (Baraya Member of the Villavieja Formation) by dr. Lundelius Ernest Jr.[21]

Museum of Geology, Colombian Geological Survey (IGM)

  • IGM 250816: Found in the Duke 57 locality in Villavieja Formation; consists of a right premaxilla and part of the maxilla, the front left tooth, part of the dorsal border of a rostrum and two vertebrae. The premaxillary measured 12.8 cm in length, is tall and thin compared to the S. icaeorhinus being covered with fine grooves on its outer surface. It has three dental alveoli in the premaxilla, from the edge of the second tooth to the fourth, which is particularly enlarged, being twice the third (reverse that in S. icaeorhinus), while the first two teeth should be small.[22] After the fourth premaxillary tooth there is a space or diastema in that fitted the fourth lower tooth that exceeded the 3.5 centimeters; has a narrow palate, lateral nasal aperture and without mild depression around.[23] The dentary is high, with four sockets, two projecting forward and a third and fourth straight, the latter being the largest. The associated vertebrae are an amphycoelian sacral with a sacral rib attached, with a wide, rectangular neural spine; it measured 10.7 cm high by 5.5 cm wide, while it is estimated that the sacral ribs should be 10 cm wide at its rear end. The other is an anterior caudal vertebrae, perhaps the first, with incomplete neural spine, with a broad neural canal, and measures 2.8 cm wide and 2.1 high. [24]
  • IGM 184 427: A tooth found in the Duke 91 locality. The crown of this is twice as high as it is wide, reaching 36 mm. high and 17 wide.[25]
  • IGM 250 541: Tooth from the Duke 196 locality, is incomplete and worn, but is similar to the tooth UCMP 40186. It measures 39 mm high by 27 wide.[26]
  • IGM 250 427: A tooth of the Duke 106 locality. It is also incomplete, but your measurements (52 mm high by 30 mm wide) makes it the largest tooth reported for a sebecosuchian in Colombia.[27]
  • IGM 184378: Tooth from Duke 40 locality. It measures 30 mm high by 17 wide.[28]
  • IGM 184 165: A tooth of the Duke 41 locality, that probably correspond to a first maxillar right tooth, measures 20 mm in height at the crown and 12 on the base, while its root has a length equivalent to 2.5 times the height of the crown. Unlike other teeth of L. huilensis, has a slight groove at the base of the tooth crown, on the inner side thereof. [29]

Department of Vertebrate Paleontology, Museum of Natural History, National University of San Marcos

  • MUSM 912: A single tooth found in the area of Fitzcarrald Arch in the localities of Inuya and Mapuya in the Amazon region of Peru; its size and shape are indistinguishable from 'L. huilensis .[30]

Museu de Ciências da Terra, Rio de Janeiro

  • MCT 1795-R/1796-R: consists of material of sebecid found in Itaboraí Basin in the state of Rio de Janeiro in Brazil. Includes a full left premaxilla with a tooth preserved, and a piece of left maxilla with two alveoli. By having very flattened and spaced teeth looks remarkably smilar to Langstonia, being provisionally classified as Sebecus cf. huilensis.[31]

Paleobiology

Due to the fragmentary remains generally known for this family, its possible only describe some general aspects of the appearance and biology of Langstonia. As mentioned above, the fossil type of the species is larger than Sebecus icaeorhinus with jaws and teeth even more flattened, although its general proportions are reminiscent of this species, which suggests that their skull would be higher and laterally flattened, in contrast to modern crocodilians, which generally have a horizontally flattened skull with conical teeth. Teeth are of the zyphodont kind, with very flattened sides, slightly curved back and with serrated edges with small denticles (between 5-6 denticles per milimeter in the teeth of this genus) and also without any grooves on its surface. This type of teeth appears in the close relatives of sebecids, the peirosaurids and baurusuchids of the Cretaceous and some crocodilians of the Cenozoic as the pristichampsids and some mekosuchines. These forms were land animals that used their teeth to cut and tear their prey, because the traditional method of capture of the crocodiles, using its pressure force to retain and drown his victims is not viable on land; these crocodylomorphs also had more elongated limbs, stiff back, ideal to hold the weight and give strength to run. Langston had already suggested that these teeth were indicative that, this animal had more terrestrial habits than those of existing species and the Miocene contemporary crocodylians, and in the modern world only could be vaguely compared with the less aquatic habits of the caimans of the genus Paleosuchus, which have a higher muzzle and a higher degree of ossification around the eye socket, so that the partially resemble sebecids.[32] Busbey suggested the fact that his skull was high implied that these animals seek no make pressure during the bite indefinitely, but to produce cuts then back quickly so that the bleeding weaken their prey slowly up to devour, similar to the current Komodo dragon, thereby adopting a strategy of stalking in areas where prey transiting frequently.[33]

In the fauna of La Venta is noted that although there were some large mammalian predators (belonging to the group of sparassodonts, as Lycopsis longirostrus and Dukecynus) any of the known equated in size to contemporary crocodylomorphs, including Langtonia[34] and given the absence of large predatory birds phorusrhacids as in the southern part of the continent, these sebecids should be the terrestrial apex predators in its ecosystem. The fossils found of other species - big fishes, manatees, large browsing meridiungulates as Granastrapotherium and Huilatherium, and some grazers as Pericotoxodon - indicate that the climate was warm and humid with heavy rainfall and with droughts periods no extending beyond 3-4 months, consisting of watersheds, forests and certain adjacent areas of open grasslands where it could hunt down a large variety of megafauna.[35]

The disappearance of the system of large rivers of the Amazon lake system and the gradual uplift of the Andes caused major ecological changes in South America in the mid-Miocene. Last sebecids, as Langstonia and Barinasuchus as apex predators in their environment, should be particularly susceptible to ecological changes that disappeared other lineages, particularly hoofed mammals (such as groups Astrapotheria, Leontiniidae, Adianthidae and Notohippidae), thus leading to extinction to the last notosuchians crocodilomorphs of the world.[36][37]

Phylogeny

Langstonia is considered part of Sebecosuchia zifodontes lineage crocodilomorphs land forming part of a separate lineage of ancient southern continent of Gondwana. As noted earlier, this species formerly part of the genus Sebecus and phylogenetic analyzes have consistently shown that these forms a clade within Sebecidae next to S. icaeorhinus and Zulmasuchus, not so closely related to Barinasuchus and Bretesuchus. Cladogram based on Pol and Powell, 2011: [38]

References

Notes

  1. ^ Cite error: The named reference APOL07 was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference langston1965 was invoked but never defined (see the help page).
  3. ^ Langston 1965, p.6
  4. ^ Langston 1965, p.14
  5. ^ Langston 1965, p.14
  6. ^ Langston 1965, p.16
  7. ^ Buffetaut and Hoffstetter, 1977; Figure 1; p. 1664
  8. ^ Busbey 1968, p. 20
  9. ^ Busbey 1986, p. 26.
  10. ^ Langston and Gasparini 1997, p.114
  11. ^ Paolillo and Jimenez 2007, p. 11.
  12. ^ Carvalho et al. 2010, p . 38
  13. ^ Salas-Gismondi, p. 356.
  14. ^ Pinheiro et al. 2011b, p. R92
  15. ^ Langston 1965, p. 15-16
  16. ^ Langston 1965, p. 17
  17. ^ Langston 1965, p.17
  18. ^ Langston 1965, p.17
  19. ^ Langston 1965, p.16
  20. ^ Langston 1965, p.17
  21. ^ Busbey 1986, p. 20
  22. ^ Langston and Gasparini 1997, p.114
  23. ^ Langston and Gasparini 1997, p.115
  24. ^ Langston and Gasparini 1997, p.116
  25. ^ Langston and Gasparini 1997, p.116
  26. ^ Langston and Gasparini 1997, p. 116-117
  27. ^ Langston and Gasparini 1997, p.116-117
  28. ^ Langston and Gasparini 1997, p.117
  29. ^ Langston and Gasparini 1997, p.117
  30. ^ Salas-Gismondi, p. 356.
  31. ^ Pinheiro' 'et al'., 2011, p. R92.
  32. ^ Langston 1965, p.134-135
  33. ^ Busbey 1986, p. 27
  34. ^ Argot 2004a, p. 513
  35. ^ Kay and Madden, p. 534-535
  36. ^ Riff et al. 2011, p. 29
  37. ^ Prevosti et al. 2013, p. 20
  38. ^ Pol and Powell, 2011

References

Cite error: A list-defined reference named "APOL07" is not used in the content (see the help page).
Cite error: A list-defined reference named "langston1965" is not used in the content (see the help page).

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