Pronunciation: BAK-tro-SOR-us
Meaning: Club lizard
Author/s: Gilmore (1933)
Synonyms: below
First Discovery: Nei Mongol, China
Discovery Chart Position: #166
Bactrosaurus johnsoni
After the discovery of fossils by Albert F. Johnson in a quarry that would later be named in his honour, Barnum Brown coined "Paraiguanodon" (meaning alongside Iguanodon) in 1923. But the name wasn't attached to a description, so it was never official. Tasked with describing the remains a decade later and realising that they didn't actually belong "alongside Iguanodon" in features or age, Charles Whitney Gilmore chose a new name, Bactrosaurus, and trumpeted it as a member of Lambeosaurine; the hadrosaurs with head crests, which was a tad strange because his own eyes told him it didn't have one.
Since then, palaeontologists have discovered a lump of bone that they think may be the remnant of a head crest, though it wasn't actually attached to a head, and so the strangeness continues. Bactrosaurus sports features typical of lambeosaurine hadrosaurids, but is small and of a surprisingly powerful build. Even with a mouthful of lozenge-shaped teeth and a bank of three available replacements for each, it still had a lower tooth count than its more advanced brethren and fewer sacral (hip) vertebrae too. All things considered, Bactrosaurus seems to be straddling an evolutionary path with the primitive iguanodonts on one side and hadrosaurids proper on the other. In other words, it's probably a hadrosauroid.
Bactrosaurus is named for the club-shaped dorsal spines that formed a visible ridge down the mid-line of its back, not Bactria; an ancient country between the Hindu Kush and the Amu Darya which is roughly modern-day Afghanistan, nor for prehistoric bacteria. But infection, it seems, was a problem. Of ten thousand dinosaur fossils that Rothschild subjected to fluoroscope screening in 2003, Bactrosaurus and its closest kin were found to be riddled with tumours, particularly the cancerous metastatic variety, and also hemangiomas, desmoplastic fibroma and osteoblastoma. Despite sounding like made-up words from cheats scrabble, these are actual diseases, and bad ones at that, the cause of which may have been environmental factors such as particular food types, or perhaps glitches in their genetics, in which case they were primed for extinction regardless.
Since then, palaeontologists have discovered a lump of bone that they think may be the remnant of a head crest, though it wasn't actually attached to a head, and so the strangeness continues. Bactrosaurus sports features typical of lambeosaurine hadrosaurids, but is small and of a surprisingly powerful build. Even with a mouthful of lozenge-shaped teeth and a bank of three available replacements for each, it still had a lower tooth count than its more advanced brethren and fewer sacral (hip) vertebrae too. All things considered, Bactrosaurus seems to be straddling an evolutionary path with the primitive iguanodonts on one side and hadrosaurids proper on the other. In other words, it's probably a hadrosauroid.
Bactrosaurus is named for the club-shaped dorsal spines that formed a visible ridge down the mid-line of its back, not Bactria; an ancient country between the Hindu Kush and the Amu Darya which is roughly modern-day Afghanistan, nor for prehistoric bacteria. But infection, it seems, was a problem. Of ten thousand dinosaur fossils that Rothschild subjected to fluoroscope screening in 2003, Bactrosaurus and its closest kin were found to be riddled with tumours, particularly the cancerous metastatic variety, and also hemangiomas, desmoplastic fibroma and osteoblastoma. Despite sounding like made-up words from cheats scrabble, these are actual diseases, and bad ones at that, the cause of which may have been environmental factors such as particular food types, or perhaps glitches in their genetics, in which case they were primed for extinction regardless.
Synonyms
"Bakesaurus" (Zhou, 2005). Nomen nudum, "naked name".
Cionodon kysylkumensis? (Riabinin, 1931)
Bactrosaurus kysylkumensis?
Initially misspelt Cionodon(?) kysylkumense, with an incorrect neuter ending, Cionodon kysylkumensis is based on a fragmentary tooth-bearing bone from the right side of the upper jaw (maxilla) that was initially misidentified as a fragmentary tooth-bearing bone from the left side of the lower jaw (dentary), four vertebrae and a shin from Djira-Kuduk, and two tail vertebrae from Khodja-Kul in the Kyzyl Kum Desert. Riabnin tentatively assigned it to Cionodon in 1931, then it travelled all over the hadrosaurian family tree, being assigned to Thespesius kysylkumense (Steel, 1969), Trachodon kysylkumense (Olshevsky, 1978) and Gilmoreosaurus kysylkumense (Nessov, 1989) before its epithet was amended to kysylkumensis by Weishampel and Horner in 1990. Then it continued its journey to Bactrosaurus kysylkumensis (Nessov, 1995). Like Cionodon, Bactrosaurus kysylkumensis is considered dubious.
(Johnson's Club Lizard)Etymology
Bactrosaurus is derived from the Greek words "baktron" (club), referring to the club-shaped spines projecting from some of its vertebrae, and "sauros" (lizard).
The species epithet, johnsoni, is a nod to Albert Johnson (see discovery).
Discovery
The first fossils of Bactrosaurus were discovered at "Johnson Quarry" (AMNH quarry 141), eight miles
to the east of the Iren Dabasu telegraph station, in the Iren Dabasu Formation of China's Gobi Desert, by Albert Johnson in 1923. The quarry contained possibly six individuals which seem to represent a clean sweep of growth stages from juvenile to geriatric.
The holotype (AMNH 6553) is the largest partial skeleton found in the quarry.
