a carnivorous tyrannosauroid theropod dinosaur from the Late Cretaceous of Mongolia.
Pronunciation: ah-LEK-tro-SOR-us
Meaning: Mateless lizard
Author/s: Gilmore (
1933)
Synonyms: None known
First Discovery: Inner Mongolia, China
Discovery Chart Position: #170
Alectrosaurus olseni
When Charles Whitney Gilmore clapped eyes on Alectrosaurus in 1933, he immediately proclaimed it "a hitherto unknown theropod" simply on the strength of its unusually long upper arms and huge hand claws.
As luck would have it, he was right. But the clawed forelimb on which he based his claim is actually the property of an as-yet unidentified member of Segnosauria while Alectrosaurus is a smooth-snouted tyrannosauroid, though one teetering on the brink of Tyrannosauridae proper.
(Olsen's Mateless lizard)Etymology
Alectrosaurus is derived from the Greek "alektros" (mateless, unmarried, or alone) and "sauros" (lizard). Confusion often stems from the similar Greek "alektor" (rooster) but
Alectrosaurus was definately no "rooster lizard!"
The
species epithet,
olseni, is a nod to George Olsen (see below).
ZooBank registry:
urn:lsid:zoobank.org:act:1D8F7D04-1197-4346-B071-040969B5BAE4.
Discovery
The first fossils of
Alectrosaurus were recovered from the
Iren Dabasu Formation (also known as
Iren nor which roughly translates as "colorful salt lake") of Nei Mongol Zizhiqu (Inner Mongolia), China, by George Olsen during the third AMNH expedition to Mongolia, on April 25th, 1923.
The
holotype (AMNH 6554) consists of a single hindlimb, proportionately weird for a "tyrant lizard"; the thigh, shin and foot were roughly the same length.
Olsen found a second specimen (AMNH 6368: a partial arm) approximately 30 meters away from the first on May 4th, 1923, that he assigned as co-type, but it belongs to something else entirely. Likewise, remains from Baishin Tsav and Uzbekistan that Perle (1977) and Nessov (1995) referred here belong elsewhere. Probably.
• Gilmore CW (1933) "
On the dinosaurian fauna of the Iren Dabasu Formation".
Bulletin of the American Museum of Natural History, 68(2-3): 23-78.
• Perle A (1977) "On the first discovery of
Alectrosaurus (Tyrannosauridae, Theropoda) in the Late Cretaceous of Mongolia".
Problems of Mongolian Geology, 3: 104–113.
• Mader BJ and Bradley RL (1989) "A redescription and revised diagnosis of the syntypes of the Mongolian tyrannosaur
Alectrosaurus olseni".
Journal of Vertebrate Paleontology, 9(1): 41-55. DOI: 10.1080/02724634.1989.10011737.
• Nessov LA (1995) "
Dinosaurs of the Northern Eurasia: new data about assemblages, ecology and paleobiogeography".
St. Petersburg State University, Institute of the Earth Crust, St.Petersburg: 1-156. DOI: 10.30906/1026-2296-1996-3-2-206-208. [English translation by Tatayana Platonov and Hans-Dieter Sues.]
• Holtz TR jr. (2001) "The phylogeny and taxonomy of the Tyrannosauridae". In Tanke and Carpenter "
Mesozoic Vertebrate Life".
• Currie PJ (2003) "Theropods from the Cretaceous of Mongolia" in Benton, Shishkin, Unwin and Kurochkin "
The Age of Dinosaurs in Russia and Mongolia".
• Holtz TR jr. (2004) "Tyrannosauroidea". In "
The Dinosauria: Second Edition".
• Carr TD (2023) "A reappraisal of tyrannosauroid fossils from the Iren Dabasu Formation (Coniacian–Campanian), Inner Mongolia, People’s Republic of China".
Journal of Vertebrate Paleontology: e2199817.
DOI: 10.1080/02724634.2023.2199817.
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To cite this page:
Atkinson, L.
"
ALECTROSAURUS :: from DinoChecker's dinosaur archive".
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http://www.dinochecker.com/dinosaurs/ALECTROSAURUS›. Web access: 06th Mar 2026.
