慈母龙属

慈母龙属; 化石时期：晚白垩世; 76.7 Ma PreЄ Є O S D C P T J K Pg N ▼
	慈母龙骨架模型，展示于布鲁塞尔自然史博物馆（英语：Brussels Natural History Museum）
科学分类
界：	动物界 Animalia
门：	脊索动物门 Chordata
纲：	蜥形纲 Sauropsida
总目：	恐龙总目 Dinosauria
目：	†鸟臀目 Ornithischia
亚目：	†鸟脚亚目 Ornithopoda
科：	†鸭嘴龙科 Hadrosauridae
亚科：	†栉龙亚科 Saurolophinae
族：	†短冠龙族 Brachylophosaurini
属：	†慈母龙属 Maiasaura; Horner & Makela,1979
模式种
	†皮氏慈母龙; Maiasaura peeblesorum; Horner & Makela,1979

慈母龙（属名：Maiasaura，由古希腊语的μαία加上拉丁语saurus的阴性拼法，意为“好妈妈蜥蜴”）是种大型鸭嘴龙科恐龙，生存于晚白垩世坎潘期（约7670万年前）的拉腊米迪亚。^[1]

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首批化石于1978年在美国蒙大拿州的双屋组（英语：Two Medicine Formation）发现，包括头骨、巢穴、蛋、胚胎以及幼体，是首次得知有明确亲代养育证据的恐龙，成为其命名由来，并以此著称。^[2]目前已发现上百具慈母龙的骨骼标本。^[3]

慈母龙体型中等，身长约9米；具有典型鸭嘴龙科的平坦喙状嘴以及深厚的鼻部；眼睛前方有小型尖状脊，可能用于繁殖季节，雄性之间的撞头比赛。^[4]近期的分类研究显示慈母龙在栉龙亚科中，可能与短冠龙最近缘，牠们一同构成短冠龙族演化支。^[5]

发现

1978年，业余古生物学家Marion Brandvold与儿子David Trexler及媳妇Laurie在蒙大拿州提顿郡肖托附近的柳溪（Willow Creek）搜寻化石。期间Marion先发现了某种恐龙幼体的骨骼，次年Laurie在同地点发现了大型头骨。^[4]

因为当初发现充满蛋壳及孵化幼体的巢穴，甚至使该遗址后来被称作“蛋山”（Egg Mountain），也是第一次发现大型恐龙会照顾后代的证据。^[4]1979年，古生物学家杰克·R·霍纳与罗伯·马凯拉（Robert Makela）命名、叙述了新属新种皮氏慈母龙（Maiasaura peeblesorum）。属名象征着养育亲子的形象，以希腊神话中的女神迈亚代表“好母亲”之意，并加上拉丁语saurus（蜥蜴）的阴性拼法saura作强调。种名纪念发现地的地主皮博斯家族（John and James Peebles）。^[2]

正模标本PU 22405是个带有部分下颌的头骨。至少有十五个个体（包括幼体）的部分骨骼被归入YPM 22400标本。

大量慈母龙的发现引起了学界对双屋组的重新关注，随后发现了更多种类的恐龙化石。^[6]提顿郡的慈母龙化石出土于比双屋组更年轻的地层，延伸其生存年代。^[7]近年在加拿大老人组（英语：Oldman Formation）也发现了慈母龙化石，进一步拓展了分布范围。^[8]

描述

慈母龙是二足兼四足行走的大型植食性恐龙，已知最大体长可达9米。具有典型鸭嘴龙科的平坦喙状嘴以及深厚的鼻部；眼睛前方有小型尖状脊，可能用于繁殖季节，雄性之间的撞头比赛。^[4]对骨骼压力承受的研究显示，四岁以下的幼体主要以双足行走，长大后转变为主要以四足行走。^[9]

分类

慈母龙属于鸭嘴龙科的栉龙亚科，其中又与短冠龙关系最亲近，牠们一同构成短冠龙族演化支。以下演化树取自皮耶妥·马奎兹（Alberto Prieto-Márquez）2013年的系统发生学研究：^[5]

栉龙亚科 Saurolophinae

短冠龙族 Brachylophosaurini

加氏始无冠龙 Acristavus gagstarsoni

	加拿大短冠龙 Brachylophosaurus canadensis

	皮氏慈母龙 Maiasaura peeblesorum

巨型山东龙 Shantungosaurus giganteus

爱德蒙托龙属 Edmontosaurus

	帝王爱德蒙托龙 Edmontosaurus regalis

	连接爱德蒙托龙 Edmontosaurus annectens

栉龙族 Saurolophini

麦氏克贝洛斯龙 Kerberosaurus manakini

Sabinas OTU

巨原栉龙 Prosaurolophus maximus

栉龙属 Saurolophus

莫氏栉龙 Saurolophus morrisi

	奥氏栉龙 Saurolophus osborni

	窄吻栉龙 Saurolophus angustirostris

分离龙族 Kritosaurini

董氏乌拉嘎龙 Wulagasaurus dongi

纳瓦霍分离龙 Kritosaurus navajovius

Big Bend UTEP OTU

	寇氏独孤龙 Secernosaurus koerneri

	萨氏南似鸭龙 Willinakaqe salitralensis

钩鼻龙属 Gryposaurus

宽齿钩鼻龙 Gryposaurus latidens

	著名钩鼻龙 Gryposaurus notabilis

	纪念区钩鼻龙 Gryposaurus monumentensis

古生物学

慈母龙通常群居行动，数量非常庞大，可能最多由一万个个体组成。^[4]慈母龙可能栖息于内陆环境。^[10]

繁衍

慈母龙是群居动物，并且在巢穴集中地孵化幼体。慈母龙的巢穴紧密排列，如同现代海鸟，巢穴之间的间隔约7米，短于成年慈母龙的身长^[11]。这些巢穴以土壤构成，中间包含30到40颗蛋，以圆形或螺旋状排列。这些蛋的大小接近鸵鸟蛋的大小^[4]。慈母龙的父母将腐烂中的植被置入巢穴中，利用腐烂产生的温度来孵化蛋，而非父母坐在巢穴中。慈母龙的幼体化石显示幼体并非发展完全，而且不能行走。化石同时显示慈母龙幼体的牙齿部分摩损，这意味者牠们的成年体将植物带回巢穴中给幼体食用^[4]。

这些成长中的幼体，在第一年里的体型从16吋到58吋长。这些幼体可能在一年后离开巢穴。这些成长中的幼体的头部比例跟成年体的比例不同，幼体有较大的眼睛与较短的口鼻部。^[4]

食性

2007年的研究指出慈母龙的食物包括单子叶植物、木本植物、腐木（英语：Dry rot）、树皮、树叶、蕨类、树枝、被子植物，代表牠同时扮演览植者（英语：Browsing (herbivory)）与刮植者（英语：Grazing (behaviour)）的生态栖位。^[12]^[13]

两性异形

Saitta等人的研究指出慈母龙其中一种性别比另一种体型大了约45％，但无法确定较大的是雄性还雌性^[14]^[15]。

古生态学

慈母龙是双屋组（英语：Two Medicine Formation）中部层位（第四层带）的指标性化石，年代约为7670万年前。^[1]在该层带慈母龙与伤齿龙科的伤齿龙、小型鸟脚类奔山龙、奔龙科的斑比盗龙、暴龙科的惧龙共存。^[1]另一种鸭嘴龙科亚冠龙在双屋组出土的层位比先前认为得还要低，显示牠们至少也与慈母龙共存过一段时间。在慈母龙出土范围内还发现另一种鸭嘴龙科宽齿钩鼻龙，代表双屋组中上部动物相之间的分界并不再像以前认为得那么明确。自从慈母龙于双屋组出现之后，当地鸟臀目物种似乎产生了大幅多样化的现象。这份对双屋组上半部暴露地层的分布情形进行的详细检验，发现多样化事件确实存在，而非化石保存上的偏差结果。^[16]虽然过去的记载经常将慈母龙与双屋组的角龙科野牛龙相提并论，^[17]^[18]但实际上两者出土的层位有所差距，慈母龙的年代相对古老许多。^[19]

大众文化

慈母龙曾出现在麦可·克莱顿（Michael Crichton）的小说《侏罗纪公园》与续集《侏罗纪公园2：失落的世界》，虽然在后来的改编电影没有出现过，但已在数个周边作品（如玩具、电子游戏）中亮相。
探索频道2003年的电视节目《恐龙星球（英语：Dinosaur Planet）》第四集出现两只慈母龙配角，是同时期惧龙的猎物。节目最后说明慈母龙演化成埃德蒙顿龙，并继续担任由惧龙演化成的暴龙主要猎物。
日本电影《你看起来很好吃》中，一只雌性慈母龙收养了一只暴龙，并将牠抚养长大。

关连项目

鸭嘴龙类研究历史（英语：Timeline of hadrosaur research）

参考来源

[1]
Horner, J. R., Schmitt, J. G., Jackson, F., & Hanna, R. (2001). Bones and rocks of the Upper Cretaceous Two Medicine-Judith River clastic wedge complex, Montana. In Field trip guidebook, Society of Vertebrate Paleontology 61st Annual Meeting: Mesozoic and Cenozoic Paleontology in the Western Plains and Rocky Mountains. Museum of the Rockies Occasional Paper (Vol. 3, pp. 3-14).
[2]
Horner, J.R.; Makela, R. Nest of juveniles provides evidence of family structure among dinosaurs. Nature. 1979, 282 (5736): 296–298. Bibcode:1979Natur.282..296H. S2CID 4370793. doi:10.1038/282296a0.
[3]
Horner, Jack and Gorman, James. (1988). Digging Dinosaurs: The Search that Unraveled the Mystery of Baby Dinosaurs, Workman Publishing Co.
[4]
"Maiasaura," Dodson, et al. (1994); pages 116-117.
[5]
Prieto-Márquez, A.; Wagner, J.R. A new species of saurolophine hadrosaurid dinosaur from the Late Cretaceous of the Pacific coast of North America. Acta Palaeontologica Polonica. 2013, 58 (2): 255–268. doi:10.4202/app.2011.0049 .
[6]
"Introduction," Trexler (2001); pages 299-300.
[7]
"Faunal Turnover, Migration, and Evolution," Trexler (2001); page 304.
[8]
McFeeters, B. D.; Evans, D. C.; Ryan, M. J.; Maddin, H. C. First occurrence of Maiasaura (Dinosauria, Hadrosauridae) from the Upper Cretaceous Oldman Formation of southern Alberta, Canada. Canadian Journal of Earth Sciences. 2020,. in press. doi:10.1139/cjes-2019-0207.
[9]
Cubo, Jorge; Woodward, Holly; Wolff, Ewan; Horner, John R. First Reported Cases of Biomechanically Adaptive Bone Modeling in Non-Avian Dinosaurs. PLOS ONE. 2015, 10 (7): e0131131. Bibcode:2015PLoSO..1031131C. PMC 4495995 . PMID 26153689. doi:10.1371/journal.pone.0131131 .
[10]
Lehman, T. M., 2001, Late Cretaceous dinosaur provinciality: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, pp. 310-328.
[11]
Palmer, D. (编). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. 1999: 148. ISBN 1-84028-152-9.
[12]
Chin, Karen. The Paleobiological Implications of Herbivorous Dinosaur Coprolites from the Upper Cretaceous Two Medicine Formation of Montana: Why Eat Wood?. PALAIOS. 1 September 2007, 22 (5): 554–566 [29 August 2020]. Bibcode:2007Palai..22..554C. JSTOR 27670451. S2CID 86197149. doi:10.2110/palo.2006.p06-087r. （原始内容存档于2022-06-09）.
[13]
"The Best of all Mothers" Maiasaura peeblesorum. bioweb.uwlax.edu/. University of Wisconsin-La Crosse. [22 March 2021]. （原始内容存档于2022-06-16）.
[14]
Using math to examine the sex differences in dinosaurs. Science Daily. [2021-10-31]. （原始内容存档于2022-06-16）（英语）.
[15]
Statistical analysis reveals differences between dinosaur sexes. [2021-10-31]. （原始内容存档于2021-10-31）.
[16]
"Faunal Turnover, Migration, and Evolution," Trexler (2001); page 306.
[17]
Weishampel, David B.; Barrett, Paul M.; Coria, Rodolfo A.; Le Loeuff, Jean; Xu Xing; Zhao Xijin; Sahni, Ashok; Gomani, Elizabeth, M.P.; and Noto, Christopher R. (2004). "Dinosaur Distribution", in The Dinosauria (2nd), pp. 517–606.
[18]
Andrew T. McDonald & John R. Horner, (2010). "New Material of "Styracosaurus" ovatus from the Two Medicine Formation of Montana". Pages 156–168 in: Michael J. Ryan, Brenda J. Chinnery-Allgeier, and David A. Eberth (eds), New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium, Indiana University Press, Bloomington and Indianapolis, IN.
[19]
Sullivan, R. M.; Lucas, S. G. The Kirtlandian land-vertebrate "age"–faunal composition, temporal position and biostratigraphic correlation in the nonmarine Upper Cretaceous of western North America. New Mexico Museum of Natural History and Science Bulletin. 2006, 35: 7–29.

延伸阅读

Dodson, Peter & Britt, Brooks & Carpenter, Kenneth & Forster, Catherine A. & Gillette, David D. & Norell, Mark A. & Olshevsky, George & Parrish, J. Michael & Weishampel, David B. The Age of Dinosaurs. Publications International, LTD. p. 116-117. ISBN 0-7853-0443-6.
Horner, Jack and Gorman, James. (1988). Digging Dinosaurs: The Search that Unraveled the Mystery of Baby Dinosaurs, Workman Publishing Co.
Lehman, T. M., 2001, Late Cretaceous dinosaur provinciality: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, pp. 310–328.
Palmer, D. (编). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. 1999: 148. ISBN 1-84028-152-9.
Trexler, D., 2001, Two Medicine Formation, Montana: geology and fauna: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, pp. 298–309.

[hornerTMF-1] [1]
Horner, J. R., Schmitt, J. G., Jackson, F., & Hanna, R. (2001). Bones and rocks of the Upper Cretaceous Two Medicine-Judith River clastic wedge complex, Montana. In Field trip guidebook, Society of Vertebrate Paleontology 61st Annual Meeting: Mesozoic and Cenozoic Paleontology in the Western Plains and Rocky Mountains. Museum of the Rockies Occasional Paper (Vol. 3, pp. 3-14).

[horner1979-2] [2]
Horner, J.R.; Makela, R. Nest of juveniles provides evidence of family structure among dinosaurs. Nature. 1979, 282 (5736): 296–298. Bibcode:1979Natur.282..296H. S2CID 4370793. doi:10.1038/282296a0.

[horner-gorman-3] [3]
Horner, Jack and Gorman, James. (1988). Digging Dinosaurs: The Search that Unraveled the Mystery of Baby Dinosaurs, Workman Publishing Co.

[ageofdinosaursmaiasaura-4] [4]
"Maiasaura," Dodson, et al. (1994); pages 116-117.

[PMetal2013-5] [5]
Prieto-Márquez, A.; Wagner, J.R. A new species of saurolophine hadrosaurid dinosaur from the Late Cretaceous of the Pacific coast of North America. Acta Palaeontologica Polonica. 2013, 58 (2): 255–268. doi:10.4202/app.2011.0049 .

[twoturn-intro-299-300-6] [6]
"Introduction," Trexler (2001); pages 299-300.

[twoturn-turnover-304-7] [7]
"Faunal Turnover, Migration, and Evolution," Trexler (2001); page 304.

[McFeeters2020-8] [8]
McFeeters, B. D.; Evans, D. C.; Ryan, M. J.; Maddin, H. C. First occurrence of Maiasaura (Dinosauria, Hadrosauridae) from the Upper Cretaceous Oldman Formation of southern Alberta, Canada. Canadian Journal of Earth Sciences. 2020,. in press. doi:10.1139/cjes-2019-0207.

[maiasaura_posture-9] [9]
Cubo, Jorge; Woodward, Holly; Wolff, Ewan; Horner, John R. First Reported Cases of Biomechanically Adaptive Bone Modeling in Non-Avian Dinosaurs. PLOS ONE. 2015, 10 (7): e0131131. Bibcode:2015PLoSO..1031131C. PMC 4495995 . PMID 26153689. doi:10.1371/journal.pone.0131131 .

[lehman-10] [10]
Lehman, T. M., 2001, Late Cretaceous dinosaur provinciality: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, pp. 310-328.

[EoDP-11] [11]
Palmer, D. (编). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. 1999: 148. ISBN 1-84028-152-9.

[12] [12]
Chin, Karen. The Paleobiological Implications of Herbivorous Dinosaur Coprolites from the Upper Cretaceous Two Medicine Formation of Montana: Why Eat Wood?. PALAIOS. 1 September 2007, 22 (5): 554–566 [29 August 2020]. Bibcode:2007Palai..22..554C. JSTOR 27670451. S2CID 86197149. doi:10.2110/palo.2006.p06-087r. （原始内容存档于2022-06-09）.

[13] [13]
"The Best of all Mothers" Maiasaura peeblesorum. bioweb.uwlax.edu/. University of Wisconsin-La Crosse. [22 March 2021]. （原始内容存档于2022-06-16）.

[14] [14]
Using math to examine the sex differences in dinosaurs. Science Daily. [2021-10-31]. （原始内容存档于2022-06-16）（英语）.

[15] [15]
Statistical analysis reveals differences between dinosaur sexes. [2021-10-31]. （原始内容存档于2021-10-31）.

[twoturn-turnover-306-16] [16]
"Faunal Turnover, Migration, and Evolution," Trexler (2001); page 306.

[DBWetal04-17] [17]
Weishampel, David B.; Barrett, Paul M.; Coria, Rodolfo A.; Le Loeuff, Jean; Xu Xing; Zhao Xijin; Sahni, Ashok; Gomani, Elizabeth, M.P.; and Noto, Christopher R. (2004). "Dinosaur Distribution", in The Dinosauria (2nd), pp. 517–606.

[McDonaldHorner-18] [18]
Andrew T. McDonald & John R. Horner, (2010). "New Material of "Styracosaurus" ovatus from the Two Medicine Formation of Montana". Pages 156–168 in: Michael J. Ryan, Brenda J. Chinnery-Allgeier, and David A. Eberth (eds), New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium, Indiana University Press, Bloomington and Indianapolis, IN.

[sullivan2006-19] [19]
Sullivan, R. M.; Lucas, S. G. The Kirtlandian land-vertebrate "age"–faunal composition, temporal position and biostratigraphic correlation in the nonmarine Upper Cretaceous of western North America. New Mexico Museum of Natural History and Science Bulletin. 2006, 35: 7–29.

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