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Lewisuchus admixtus
Taxonomy
Lewisuchus admixtus was named by Romer (1972). Its type specimen is MLP 64-XI-14-14 and is a compression fossil. Its type locality is Chañares River, 4 km north, which is in a Ladinian fluvial-lacustrine horizon in the Chañares Formation of Argentina.
Entered
by M. Carrano on 2005-09-21; modified by M. Carrano on 2021-06-29
Synonyms
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Synonymy list
| Year | Name and author |
|---|---|
| 1972 | Lewisuchus admixtus Romer |
| 1978 | Lewisuchus admixtus Bonaparte p. 297 |
| 1979 | Lewisuchus admixtus Bonaparte p. 220 |
| 1987 | Pseudolagosuchus major Arcucci |
| 1988 | Lewisuchus admixtus Paul p. 242 |
| 1988 | Pseudolagosuchus major Paul pp. 244-245 |
| 1991 | Pseudolagosuchus major Olshevsky p. 103 |
| 1991 | Pseudolagosuchus major Sereno p. 23 |
| 1993 | Lewisuchus admixtus Parrish p. 297 |
| 1995 | Pseudolagosuchus major Bonaparte p. 82 |
| 1997 | Lewisuchus admixtus Arcucci p. 181 |
| 1997 | Pseudolagosuchus major Arcucci p. 181 |
| 1997 | Pseudolagosuchus major Novas p. 678 |
| 2006 | Pseudolagosuchus major Ezcurra p. 657 fig. 3 |
| 2009 | Pseudolagosuchus major Bittencourt and Kellner p. 20 |
| 2010 | Lewisuchus admixtus Langer et al. p. 58 |
| 2010 | Pseudolagosuchus major Langer et al. p. 58 |
| 2011 | Pseudolagosuchus major Nesbitt |
| 2011 | Lewisuchus admixtus Nesbitt p. 46 |
| 2012 | Lewisuchus admixtus Kammerer et al. p. 277 |
| 2012 | Pseudolagosuchus major Kammerer et al. p. 277 |
| 2014 | Lewisuchus admixtus Bittencourt et al. p. 191 |
| 2014 | Lewisuchus admixtus Marzola and Dalla Vecchia p. 13 |
| 2014 | Pseudolagosuchus major Mocho et al. |
| 2016 | Pseudolagosuchus major Griffin and Nesbitt p. 10 |
| 2016 | Lewisuchus admixtus Martínez et al. p. 2 |
| 2019 | Lewisuchus admixus Martz and Small p. 52 |
| 2019 | Pseudolagosuchus major Martz and Small p. 52 |
| 2019 | Lewisuchus admixtus Veiga et al. p. 10 |
| 2020 | Lewisuchus admixtus Ezcurra et al. p. 1397–1398 |
| 2024 | Lewisuchus admixtus Fonseca et al. |
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
†Lewisuchus admixtus Romer 1972
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Invalid names: Pseudolagosuchus major Arcucci 1987 [synonym]
Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| A. B. Arcucci 1987 (Pseudolagosuchus major) | Moderately sized lagosuchid (femur 11.5 cm long); with axially elongated presacral, sacral and caudal vertebrae, much longer than in Lagosuchus, the last with tall neural spines. Pubis as long as the femur, with symphysis more extended longitudinally than in Lagosuchus, and with strong process for the ambiens. Femur robust and somewhat shorter than the tibia. Femur-tibia ratio 0.94, greater than in Lagosuchus. Distal articulation of the tibia of quadrangular shape, lacking the posterior descending process observed in Lagosuchus. Fibula extended anteroposteriorly and reduced relative to the tibia. Tibia with fossa or recess in its distolateral portion, more marked than in Lagosuchus. Mesotarsal tarsus, with quadrangular astragalus, with marked ascending process and a more developed posterior tuberosity on the lateral border of this bone than in Lagosuchus. Reduced calcaneum, conical in shape and with vestiges of the tubercle, which is inclined laterally and posteriorly, as in Lagosuchus. (Translated by M. Carrano.) | |
| A. B. Arcucci 1997 (Pseudolagosuchus major) | Medium-sized archosaur with pubis longer than femur, elongated proximal caudal vertebrae?, and rounded process projected from the posterior face of the astragalus. | |
| A. B. Arcucci 1997 | Small archosaur with elongated cervical vertebrae, long and narrow scapular blade, small oval dermal scutes on the cervical, and dorsal neural spines. | |
| J. S. Bittencourt et al. 2014 | Dinosauromorph that can be distinguished from its kin by the following combination of features (asterisks indicate potential autapomorphies): extremely elongated skull, supraoccipital nearly horizontal, three foramina caudal to the metotic strut*, craniocaudally extending rugose ridge on the mid-height of the lateral surface of the axial neural spine*, postzygodiapophyseal lamina of the caudal cervical vertebrae projecting caudally to the tip of the postzygapophysis, and the presence of a single row of scutes associated to the distal tip of the cervical and dorsal neural spines. | |
| M. D. Ezcurra et al. 2020 | Lewisuchus admixtus is an early diverging dinosauriform that differs from other Triassic archosauromorphs in the following combination of character-states (autapomorphies indicated with an asterisk and the specimens that possess the character-state are indicated between brackets, uncited specimens does not preserve the region or structure; PULR-V 112 and PULR-V 113 are not included in this list): premaxillary tooth crowns conical and without serrations (CRILAR-Pv 552); proportionally large skull, in which the length of the maxilla equals 0.71 the length of the scapula and 0.61 the length of the tibia* (PULR 01, CRILAR-Pv 552); first seven maxillary tooth crowns without mesiodistally expanded bases and mesial serrations, with distal serra- tions orthogonal to the margin of the crown, and four faint and nearly longitudinal ridges at the base of the crown that converge toward the apex on both lingual and labial surfaces* (CRILAR-Pv 552); three foramina posterior to the metotic strut* (PULR 01); anteroposteriorly extending rugose ridge on the middle height of the lateral surface of the axial neural spine* (PULR 01); coracoid portion of the glenoid fossa slanting mainly laterally (in comparison with other dinosauriforms)* (PULR 01, CRILR-Pv 552); absence of coracoid foramen, at least in the posterior two-thirds of the bone* (PULR 01, CRILR-Pv 552); ilium with a shallow and ventrally facing brevis fossa (CRILAR-Pv 552); pubes with a rod-like shaft and a median notch between their distal ends, so that the distalmost ends of the pubes do not meet on the midline (CRILAR-Pv 552, PVL 4629); femoral head without a longitudinal groove on its proximal surface, has a well-developed trochanteric fossa and anteromedial tuber, and is moderately medially offset, with a square profile, and a notch separating it from the shaft in anterior or posterior view (CRILAR-Pv 552, MACN-Pv 18954, PULR 053, PVL 4629); femur with a popliteal fossa that extends proximally less than 1/4 the length of the bone (PULR 053, PVL 3464); fibula with a tab-like, medially projected process at the level of the iliofibularis tubercle* (CRILAR-Pv 552); astragalus with subequally projected anterolateral and posterolateral processes, and without a well-rimmed fossa posterior to the ascending process (MACN-Pv 18954, PVL 3454); calcaneum with a calcaneal tuber poorly posteriorly projected from the fibular facet (MACN-Pv 18954); and presence of a single row of elongated ossifications (osteoderms sensu Romer (1972) and Bittencourt et al. (2014)) on the distal surface of the post- axial cervical and, at least, first nine dorsal neural spines* (PULR 01). |
Measurements
No measurements are available
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| Source: o = order | |||||
| References: Kiessling 2004, Marsh 1875 | |||||
Age range: base of the Longobardian to the top of the Ladinian or 239.48000 to 237.00000 Ma
Collections (4 total)
| Time interval | Ma | Country or state | Original ID and collection number |
|---|---|---|---|
| Ladinian | Argentina (La Rioja) | Lewisuchus admixtus (type locality: 13271) Pseudolagosuchus major (105535) | |
| Longobardian - Julian | Argentina (La Rioja) | Lewisuchus admixtus (205839) | |
| Longobardian - Judithian | Argentina (La Rioja) | Pseudolagosuchus major (26092) |