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a plant-eating hadrosaurid dinosaur from the Late Cretaceous of North America.
Pronunciation: MAY-ya-SOR-uh
Meaning: Good mother lizard
Author/s: Horner and Makela (1979)
Synonyms: None known
First Discovery: Montana, USA
Chart Position: 215

Maiasaura peeblesorum

Until the 1970s, dinosaurs had a terrible reputation as not-very-bright, sluggish grunters, who just lazed around waiting to go extinct. However, the discovery of Deinonychus started something of a dinosaur renaissance by proving that members of the theropod branch were agile, warm-blooded, intelligent predators. Not to be outdone, Maiasaura flew the flag for vegetarians, and showed that some members of the ornithopod branch had strong maternal instincts, and were good housekeepers to boot.

The first known fossil of Maiasaura was a single skull discovered by Marion (Trexler) Brandvold in 1978, but within a few short years the discoveries had snowballed into "Egg Mountain" — a Montana breeding ground full of volcano-shaped nests with up to twenty, kilo-weight eggs a piece, and a clean sweep of growth stages from embryo to geriatric. The nests were neatly arranged in rows with just enough room for a sentinel adult to march between, and contained fossilized evidence to prove that Maiasaura — meaning good mother lizard — were indeed good mothers. Even the fathers. Possibly.

Fossil remains within some nests did not belong to hatchlings but to young juveniles, suggesting the offspring were altricial (nest bound) for some time after they emerged from their shells.|1| The leg joints of the typically short-snouted, large-eyed, cutesy kids had not properly formed so they could not fend for themselves. And yet their teeth sported wear patterns that only arrive with chewing. Food was being delivered to them by molly-coddling adults.

For the colossally-proportioned, thick-nosed, "duck-billed" parents — nine meters long, two meters high, and a couple of tons in weight — brooding would be a dangerous game, so they didn't bother. In a manner still observed in some modern birds and crocodiles, the crucial task of incubation was left to the soft plant matter used to pack and cover the nests, which warmed the eggs during fermentation, just like a steaming, stinking, compost heap. After that it was power-eating ahoy, and paleontologists reckon Maiasaura grew from the size of a rabbit to the size of a deer in around a year, at which point they were strong enough to find their own food.
(The Peeble's good mother lizard)Etymology
Maiasaura combines the Greek terms "maia" (good mother or nurse) and "saura" (female form of the male "sauros", meaning "lizard". The species epithet, peeblesorum, honors the Peebles family—the ranchers who (1) owned the land that Marion Brandvold found the first baby specimen in the 1980s, and (2) became understandably miffed at the amount of thieving trespassers that the publicity attracted.
The first fossils of Maiasaura were discovered in the Two Medicine Formation of Montana in 1978 by Marion (Trexler) Brandvold who died on Thursday June 5th, 2014, at the ripe old age of 102. The holotype (PU 22405) is a skull.
Fossilised coprolites (poop) from one particular site in the Two Medicine Formation were attributed to Maisaura and studied in 2007 by Karen Chin who concluded that they contained a surprisingly high percentage of rotting conifer wood. Accidental ingestion as Maisaura nibbled on the leaves and fine twigs of a terminal tree were ruled out, as there were no identifiable twigs present. But why expend precious energy deliberately chewing lumps of wood that hold little to no nutritional value for vertebrates? Well, it wasn't the rotting wood they were after, but the resources contained within. Fungus and tiny creepy-crawlies make rotting wood their home, and would have provided nutritious tit-bits to keep the coprolite producers going, perhaps through the winter season when grasses and foliage were in short supply.
Era: Mesozoic
Epoch: Late Cretaceous
Stage: Campanian
Age range: 80-75 mya
Est. max. length: 9 meters
Est. max. hip height: 2.3 meters
Est. max. weight: 2.5 tons
Diet: Herbivore
• J. R. Horner and R. Makela (1979) "Nest of juveniles provides evidence of family structure among dinosaurs."
• D. Trexler (2001) "Two Medicine Formation, Montana: geology and fauna" in D.H. Tanke and K. Carpenter (eds.) "Mesozoic Vertebrate Life".
• Horner, Jack and Gorman, James. (1988) "Digging Dinosaurs: The Search that Unraveled the Mystery of Baby Dinosaurs".
• Philip J. Currie & Kevin Padian (1997) "Encyclopedia of Dinosaurs".
• D.B. Weishampel, P.M. Barrett, R.A. Coria, J. Le Loeuff, Xu Xing, Zhao Xijin, A. Sahni, E.M.P. Gomani and C.R. Noto (2004) "Dinosaur Distribution" in "The Dinosauria: Second edition".
• Chin K (2007) "The Paleobiological Implications of Herbivorous Dinosaur Coprolites from the Upper Cretaceous Two Medicine Formation of Montana: Why Eat Wood?". PALAIOS. 22 (5): 554.
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To cite this page:
Atkinson, L. "MAIASAURA :: from DinoChecker's dinosaur archive".
›. Web access: 16th Dec 2017.