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Amphicoelias
Taxonomy
Amphicoelias was named by Cope (1877).
It was synonymized subjectively with Morosaurus by Sauvage (1880); it was synonymized subjectively with Camarasaurus by Sauvage (1882), Marsh (1895), Marsh (1896), Marsh (1898).
It was assigned to Amphicoeliidae by Cope (1877), Cope (1878); to Cetiosauridae by Cope (1891), Cope (1898); to Atlantosauridae by Zittel (1890), Nopcsa (1901), Hay (1902), Huene (1908), Huene (1908); to Opisthocoelia by Osborn and Mook (1919); to Morosauridae by Huene (1927), Huene (1927), Huene (1929); to Sauropoda by Williston (1878), Tatarinov (1964); to Titanosauridae by Romer (1966); to Diplodocinae by Romer (1956), Steel (1970), Coombs and Molnar (1981), McIntosh (1990), Bakker (1996), Salgado (1999); to Diplodocoidea by Wilson and Smith (1996), Wilson (2002), Upchurch et al. (2004), Whitlock (2011), Mannion et al. (2012), Tschopp and Mateus (2013); to Diplodocidae by Nopcsa (1928), Hay (1930), Paul (1988), McIntosh (1997), McIntosh (2005), Chure et al. (2006), Galiano and Albersdörfer (2010), Galiano and Albersdörfer (2010), Tschopp et al. (2015); to Apatosaurinae by Tschopp and Mateus (2017); and to Diplodocoidea by Mannion et al. (2019), Mannion et al. (2021).
It was synonymized subjectively with Morosaurus by Sauvage (1880); it was synonymized subjectively with Camarasaurus by Sauvage (1882), Marsh (1895), Marsh (1896), Marsh (1898).
It was assigned to Amphicoeliidae by Cope (1877), Cope (1878); to Cetiosauridae by Cope (1891), Cope (1898); to Atlantosauridae by Zittel (1890), Nopcsa (1901), Hay (1902), Huene (1908), Huene (1908); to Opisthocoelia by Osborn and Mook (1919); to Morosauridae by Huene (1927), Huene (1927), Huene (1929); to Sauropoda by Williston (1878), Tatarinov (1964); to Titanosauridae by Romer (1966); to Diplodocinae by Romer (1956), Steel (1970), Coombs and Molnar (1981), McIntosh (1990), Bakker (1996), Salgado (1999); to Diplodocoidea by Wilson and Smith (1996), Wilson (2002), Upchurch et al. (2004), Whitlock (2011), Mannion et al. (2012), Tschopp and Mateus (2013); to Diplodocidae by Nopcsa (1928), Hay (1930), Paul (1988), McIntosh (1997), McIntosh (2005), Chure et al. (2006), Galiano and Albersdörfer (2010), Galiano and Albersdörfer (2010), Tschopp et al. (2015); to Apatosaurinae by Tschopp and Mateus (2017); and to Diplodocoidea by Mannion et al. (2019), Mannion et al. (2021).
Species
Synonymy list
| Year | Name and author |
|---|---|
| 1877 | Amphicoelias Cope p. 3 |
| 1878 | Amphicoelias Cope p. 76 |
| 1878 | Amphicoelias Williston p. 45 |
| 1890 | Amphicoelias Zittel p. 709 |
| 1891 | Amphicoelias Cope p. 43 |
| 1898 | Amphicoelias Cope p. 69 fig. 22 |
| 1901 | Amphicoelias Nopcsa p. 203 |
| 1902 | Amphicoelias Hay p. 486 |
| 1908 | Amphicoelias Huene p. 297 |
| 1919 | Amphicoelias Osborn and Mook p. 383 |
| 1927 | Amphicoelias Huene p. 123 |
| 1928 | Amphicoelias Nopcsa p. 184 |
| 1929 | Amphicoelias Huene p. 117 |
| 1930 | Amphicoelias Hay p. 200 |
| 1956 | Amphicoelias Romer p. 624 |
| 1964 | Amphicoelias Tatarinov p. 549 |
| 1966 | Amphicoelias Romer p. 370 |
| 1970 | Amphicoelias Steel p. 80 |
| 1981 | Amphicoelias Coombs, Jr. and Molnar p. 356 |
| 1988 | Amphicoelias Paul p. 11 |
| 1990 | Amphicoelias McIntosh p. 391 |
| 1996 | Amphicoelias Bakker p. 44 |
| 1996 | Amphicoelias Wilson and Smith p. 73A |
| 1997 | Amphicoelias McIntosh p. 657 |
| 1999 | Amphicoelias Salgado p. 204 |
| 2002 | Amphicoelias Wilson p. 248 |
| 2004 | Amphicoelias Upchurch et al. p. 265 |
| 2005 | Amphicoelias McIntosh p. 74 |
| 2006 | Amphicoelias Chure et al. p. 236 |
| 2010 | Amphicoelias Galiano and Albersdörfer pp. 5-7 |
| 2011 | Amphicoelias Whitlock |
| 2012 | Amphicoelias Mannion et al. |
| 2013 | Amphicoelias Tschopp and Mateus p. 877 fig. 11 |
| 2015 | Amphicoelias Tschopp et al. |
| 2017 | Amphicoelias Tschopp and Mateus |
| 2019 | Amphicoelias Mannion et al. |
| 2021 | Amphicoelias Mannion 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.
G. †Amphicoelias Cope 1877
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†Amphicoelias altus Cope 1877
†Amphicoelias brontodiplodocus Galiano and Albersdörfer 2010
Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| H. Galiano and R. Albersdörfer 2010 | The genus Amphicoelias differs from other diplodocid genera in the following characteristics of primitive and derived features. Skull microcephalomorph, rostrum long; premaxillae caudally elongate, quadrate rostroventrally inclined; external nares opening dorsally above orbits; basipterygoid processes slender and elongate, occipital condyle ventrally positioned. Upper and lower teeth reduced in number and modified into sub-equal lengths of crown and root that are long and slender, spaced apart and retained in front of jaws; jaws behind preantorbital fenestrae edentulous. mandible long slender with expended symphysis. Fifteen cervical vertebrae, 2nd-15th elongated with 14th process being the longest centrum, ten free dorsals, sacrum normally comprised of one dorsal, two sacral and two caudal vertebrae. First dorsal in the series has the longest centrum, 10th dorsal with neural spine body off alignment with centrum, posterior dorsals, sacrum and anterior caudal vertebrae all with tall neural spines. Sacral vertebrae with ventral keels. three sectioned diverse caudal morphology, anterior caudals with pleurocoels (suppressed or absent in males) and expanded transverse processes; centrum of anterior caudals gradually decreasing posteriorly in size until, at a mid-point, they increase in size and robustness from (16th-20th) before decreasing again in size where they meet the supernumerary whiplash series. the approximately forty or so supernumery caudals are sub-equal in length. the location of enlarged mid caudals or "disproportionately enlarged" transitional series is variable. Caudal fusion is also variable depending on the individual and age, and can occur in singles or in sets of two. Compact bone construction is dense in posterior caudals starting from "disproportionately enlarged" series. Anterior chevrons without anterior processes but remaining posterior ones diversely shaped depending on the location of the tail, starting in mid-tail from a simple elongated paddle then to forked and rod-like “double beam” shape types. Anterior processes become greater in size towards the end, and reach a near equal length with the main chevron body. Forked chevrons usually located below in restricted areas within mid caudal series; ischia distal ends expanded; femur elongated, straight with reduced 4th trochanter and cross section sub circular to ovate. Sternal ribs ossified. | |
| H. Galiano and R. Albersdörfer 2010 | Amphicoelias differs from all other diplodocids in the extreme microcephalomorph condition of the skull in relation to the length of the axial skeleton in mature individuals. In comparison to other sauropods, the skull in Amphicoelias has proportionately the longest rostrum relative to the post-orbital length. Thus, the premaxillae are caudally elongated and the anterior-posterior length of the nasal and frontal bones are reduced and receded, more so than in other sauropods. The Amphicoelias skull is characterized by a rostral crest formed by the caudal processes of the premaxillae (autapomorphy), and with the premaxillae and maxillae transversely extended and flattened forming a duck billed shaped rostrum. Presence of the external narial openings located posterior-dorsal almost above orbits (synapomorphy). Amphicoelias differs from all sauropods in the development of an interfenestra bridge dividing the preantorbital from the antorbital fenestrae (autapomorphy). In Amphicoelias, Nigersaurus, and Tornieria the preantorbital fenestrae are positioned immediately behind the last maxillary tooth. There are two preantorbital openings present in the maxilla of Nemegtosaurus distinguishing it from Amphicoelias Pterygoid bones in Amphicoelias are sagitally positioned at a steep angle in comparison to other known sauropod skulls. Amphicoelias shares with the diplodocid genera Tornieria, and Dicraeosaurus, the following derived sauropod characters: occipital condyle ventrally positioned; quadrates rostroventrally inclined; basipterygoid processes slender, elongate and oriented rostroventrally; and jaws behind preantorbital fenestra are without teeth. |
Measurements
No measurements are available
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| Source: g = genus, infrao = infraorder | |||||
| References: Peczkis 1995, Marsh 1875 | |||||
Age range: base of the Late/Upper Oxfordian to the top of the Early/Lower Tithonian or 157.90000 to 145.06000 Ma
Collections (3 total)
| Time interval | Ma | Country or state | Original ID and collection number |
|---|---|---|---|
| Late/Upper Oxfordian - Early/Lower Kimmeridgian | USA (Wyoming) | A. brontodiplodocus (126540) | |
| Early/Lower Tithonian | USA (Colorado) | A. altus (48154) | |
| Tithonian | Zimbabwe (Mashonaland North) | A. sp. (49105) |