Maiasaura (from the Greek "μαία + σαύρα", meaning "caring mother lizard") is a large duck-billed dinosaur genus that lived in the area currently covered by the state of Montana in the Cretaceous Period, about 77-74 million years ago in what is now The Two Medicine Formation. It was one of the last non-avian dinosaurs, and lived alongside Triceratops and Tyrannosaurus shortly before the Cretaceous–Tertiary extinction event.[1][2][3]
The Dinosaur get's it's name from the term good mother lizard. This comes from some various evidence that seems to indicate that they cared for their hatchlings, one of the more rarer direct evidence that we've encountered in the Cretaceous Paleontological Record, a rare sight among dinosaurs, primarily in the herbivorous group however.
Description[]
Maiasaura was large, growing up to 9 metres (30 ft) long and had the typical hadrosaurid flat beak and a thick nose. It had a small, spiky crest in front of its eyes. The crest may have been used in headbutting contests between males during the breeding season, for lacking the majestic headgear of its related animals. The fleshy bumps are equally impressive. Alas, the bony less fragile headgear of this hadrosaurid must've supported more stability. Just like other Hadrosaurids though, the Maiasaura may have also slapped necks together during mating season as well.
This dinosaur was an herbivore. It walked both on two or four legs and seemed to have no defense from predators, though its heavy muscular tail and its herd behaviour both could have been one. These herds were quite large and could have been made up of as much as 10,000 individuals,[4] Maisaura lived in an inland habitat.[5] although the Late Cretaceous North American Seaway might've provided a natural source of water for these animals. [6] The rather moist environment provided immense amounts of plants, and foliage for the Maiasaura to eat, leading to a relatively stable diet. Such were the stable diets of many Late Cretaceous North American herbivores like Triceratops and Pachycephalosaurus.
History[]
Maiasaura was discovered by Laurie Trexler and described by dinosaur paleontologist Jack Horner (paleontologic advisor for the Jurassic Park movies) and Robert Makela. He named the dinosaur after Marion Brandvold's discovery of a nest with remains of eggshells and babies too large to be hatchlings. These discoveries led to others, and the area became known as "Egg Mountain", in rocks of the Two Medicine Formation near Choteau in western Montana. Careful examination and study of the fossil site led to several discoveries and insights regarding the nurturing habits of Maiasaura, as well as other dinosaurs. Many of the excavated Maiasaura skeletons were particularly large; clearly too large to be hatchlings, which lead to the conclusion that even after hatching, young Maiasaura lived with the herd. Evidence for this form of parental care is also seen in close examination of the leg bones of young Maiasaura, showing that they were not fully formed when the animals hatched, similar to hatchling modern birds, in that the bones of hatchlings lacked well-ossified ends, and and instead ended in calcified cartilage pads.[1][2] As a result of this, the hatchlings were most likely confined to their nest for upwards of a few weeks. This was the first proof of giant dinosaurs raising and feeding their young.[7] Over 200 specimens, in all age ranges, have been found.[8] The announcement of Maiasaura's discovery attracted renewed scientific interest to the Two Medicine Formation and many other new kinds of dinosaurs were discovered as a result of the increased attention.[9] Choteau Maiasaura remains are found in higher strata than their Two Medicine River counterparts.[10]
Classification[]
The closest phylogenetic relation of the genus Maiasaura seems to fall with Brachylophosaurus . To reflect on this, both are in the same tribe, and are thus differentiated from the other components of this subfamily: Aralosaurus, Hadrosaurus and Gryposaurus .
Recently, along with Brachylophosaurus and Acristavus, Maiasaura was located in a new clade called Brachylophosaurini .[11]
Hadrosaurinae |
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Hadrosaurinae |
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Paleobiology[]
The rapid growth of Maiasaura has led many paleontologists to suggest that Maiasaura was warmblooded.[1]
Growth rates[]
Maiasaura varies ontogenetically, in that juvenile and adolescent Maiasaura growth rates indicate highly vascularized woven bone. based on analyses of several specimens, ranging from hatchlings to fully grown adults, it is widelt accepted that Maiasaura reached approximately nine feet in length during its first year. This is consistent with the growth rates of modern-day flightless birds that are warm-blooded, and is faster than the growth rates of cold-blooded reptiles.
Reproduction[]
Maiasaura lived in herds and it raised its young in nesting colonies. The nests in the colonies were packed close together, like those of modern seabirds, with the gap between the nests being around 7 meters (23 ft); less than the length of the adult animal.[12] The nests were made of earth or sand, and was repeatedly layered, so as to provide concealment of the eggs from potential predators, and to aid in egg incubation. The nests contained anywhere from 30 to 40 eggs, all laid in a circular or spiral pattern within the nest. The eggs were about the size of ostrich eggs.
The eggs were incubated by the heat caused by rotting vegetation placed into the nest by the parents, rather than a parent sitting on the nest. Fossils of baby Maiasaura show that, when they hatched, their legs were not fully developed and thus they could not leave the nest. Fossils also show that their teeth were partly worn, which means that the adults brought food to the nest.
The hatchlings grew from a size of 16 to 58 inches long in the span of their first year. At this point, or perhaps after another year, the animal left the nest. This high rate of growth may mean they were warm blooded. The hatchlings had different facial proportions from the adults, with larger eyes and a shorter snout.[13] These traits are associated with cuteness and are common in animals that depend on their parents when they are young.
Parental care[]
Evidence for parental care in Maiasaura has also been seen in close examination of the leg bones of young Maiasaura, showing that they were not fully formed when the animals hatched, similar to hatchling modern birds.[1][2] As a result of this, the hatchlings were most likely confined to their nest for upwards of a few weeks. This is evidenced by the presence of trampled eggshell remains within the nests. If the hatchlings had left the nest as soon as they had hatched, then the eggshells would be left more intact.
Newborn Maiasaura were approximately 12 inches (30 cm) in length, however, by approximately three to five weeks after hatching, the Maiasaura were in lengths of upward of 5 feet (1.5 m) long, and were capable of leaving the nest on their own. Maiasaura grew from a size of 16 to 58 inches (41 to 150 cm) long in the span of their first year. This high rate of growth may be evidence of warm bloodedness. The hatchlings had different facial proportions from the adults, with larger eyes, a shorter snout, and as they grew older, developed a flatter and wider head.[1][2] These features are associated with cuteness and are common among animals that are dependent on their parents' for survival during the early stages of life.
The individual nests varied in size, but were usually in the range of 10 feet (3 m) in diameter and about 5 feet (1.5 m) in height. The interior of the fossil nest was approximately 6 feet (2 m) in diameter and approximately 2 feet (0.75 m) deep. The average spacing between these nests was about 23 feet (7 m), which indicates that Maiasaura mothers nested close together, as the average size of an adult varied from 26-30 feet (7-8 m). Several Maiasaura specimens have been found in bone-beds that cover miles in some cases. The large number of fossilized specimens in these bone-beds lets paleontologists conclude that Maiasaura nested in colonies.
So far, only the hadrosaurs Maiasaura and Hypacrosaurus, along with an unidentified Argentine sauropod, and unidentified Portugese theropod, a possible therizinosaur, Oviraptor, and Troodon are the only known dinosaurs that have been discovered near clutches of eggs, caring for their young.
Contemporaries[]
In the Two Medicine Formation, Maiasaura lived alongside the tyrannosaur Daspletosaurus, the oviraptorosaur Chirostenotes, a troodontid (possibly Stenonychosaurus), the dromaeosaurs Bambiraptor and Saurornitholestes, the enantiornithe bird Avisaurus, the nodosaur Edmontonia, the ankylosaur Euoplocephalus, the ceratopsids Achelousaurus, Brachyceratops, Einiosaurus, and Styracosaurus ovatus, the hypsilophodont Orodromeus, and the hadrosaurids Hypacrosaurus stebingeri and Prosaurolophus.[14] Hypacrosaurus coexisted with Maiasaura for some time, as Hypacrosaurus remains have been found lower in the Two Medicine Formation than was earlier known. The discovery of Gryposaurus latidens in Maiasaura's range has shown that the border between theorized distinct faunas in the upper and middle is less distinct than once thought. There seems to be a major variation in ornithischian taxa after the appearance of Maiasaura within the Two Medicine Formation. The close examination of strata found along the Two Medicine River (which exposes the entire upper half of the Two Medicine Formation) indicates that the apparent variation was a real event rather than from preservational biases.[15]
Paleoecology[]
Maiasaura lived in Montana during the Late Cretaceous. Individuals lived in massive herds, that laid eggs once every month. Maiasaura cared for their young. Males bore a head crest for headbutting competitions, though had no defenses against predators.
A specimen auctioned off by Heritage Auctions, labelled as M. sp., is stated to be from the Hell Creek Formation. The specimen was inferred to be closer to but earlier than M. peeblesorum; however, Maiasaura lived millions of years before the Hell Creek fauna, so this must be untrue. The skull and jaw is in good condition with all teeth present and preserved in the upper jaw. The skull, after preparation, is reportedly 25 inches long. The braincase was also found, 5.5 inches long, with intact large, round olfactory lobes. It was found by a fossil collector whose daughter located a strange object, which turned out to be the skull. It was found disarticulated, the braincase partially embedded in rock. However, it is unlikely Maiasaura are present in Hell Creek. Some have noted a majority of the skull looks restored, with the presumed fossil parts assumed to be lambeosaurine, possibly of the Hell Creek lambeosaur. It may also be an amateur mistake or a lie used by the auction house used because Hell Creek is a popular geologic formation. Nonetheless, the skull was sold on September 28, 2014.
JPInstitute.com Description[]
Maiasaura is one of the most famous of the duck-billed dinosaurs because it proved to many scientists that dinosaurs had nests, nesting grounds and took care of their young. It was a medium-sized member of the duck-billed hadrosaur family, which included Parasaurolophus and Lambeosaurus. More than 200 specimens of this dinosaur have been discovered, making it one of the best known. What is especially interesting is that many babies and young adults have been found.
Jack Horner's discovery of Maiasaura set the world of paleontology on fire and also rekindled public interest in dinosaurs. Until its discovery, most scientists thought that dinosaurs laid their eggs, left them on their own to hatch and then let the babies fend for themselves. The nests Horner discovered seem to clearly show evidence of babies that remained in the nest for some time and would have been cared for by adults.
Apart from the spectacular nature of its discovery, and the number of specimens, Maiasaura was a fairly typical, mid-sized hadrosaur. It had no real crest, but it did have a small spike-like crest in front of its eyes.
Appearance in other media[]
Jurassic Park[]
- Maiasaura appeared in Jurassic World: Alive as an Epic creature. Its thought to be very popular among mid-level players due to its Instant Rampage move.
- Maiasaura appeared in Jurassic World: Evolution, and is accessible after moving into the island, Isla Tacano, and the sequel, Jurassic World: Evolution 2.
Read more Maiasaura on Jurassic Park Wiki |
The Land Before Time[]
- Some Maiasaura appeared in The Land Before Time Movies. They even appeared in most episodes of the Land Before Time TV Series too.
Read more Maiasaura on Land Before Time Wiki |
Links[]
References[]
- ↑ 1.0 1.1 1.2 1.3 1.4 Brochu, Christopher A.. (2002). A Guide to Dinosaurs. San Francisco, CA: Fog City Press. p. 185. ISBN 1-876778-63-6
- ↑ 2.0 2.1 2.2 2.3 Cite error: Invalid
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- ↑ https://phys.org/news/2023-10-holes-baby-dinosaur-bones-football-sized.html
- ↑ "Maiasaura," Dodson, et al.(1994); pages 116-117.
- ↑ "Judithian Climax," Lehman (2001); page 315.
- ↑ "Judithian Climax," Lehman (2001); page 315.
- ↑ "Maiasaura," Dodson, et al.(1994); pages 116-117.
- ↑ Horner and Gorman (1988).
- ↑ "Introduction," Trexler (2001); pages 299-300.
- ↑ "Faunal Turnover, Migration, and Evolution," Trexler (2001); page 304.
- ↑ Gates, T.A.; Horner, J.R.; Hanna, R.R.; and Nelson, C.R. (2011). «New unadorned hadrosaurine hadrosaurid (Dinosauria, Ornithopoda) from the Campanian of North America». Journal of Vertebrate Paleontology 31 (4): pp. 798-811. doi:10.1080/02724634.2011.577854.
- ↑ Palmer (1999); page 148.
- ↑ "Maiasaura," Dodson, et al.(1994); pages 116-117.
- ↑ Weishampel, et al. (2004); pages 517–606.
- ↑ Faunal Turnover, Migration, and Evolution," Trexler (2001); page 306