霸王龍復(fù)原標(biāo)本模型：（A）右側(cè)位，（B）背部,，（C）顱骨,，（D）右側(cè)面
恐龍身體上的脂肪應(yīng)當(dāng)有多少,？目前科學(xué)家使用激光成像技術(shù)測(cè)定出恐龍的“標(biāo)準(zhǔn)體重”,。相關(guān)論文發(fā)表在《公共科學(xué)圖書館·綜合》（PLoS ONE）雜志上,。
恐龍是巨型動(dòng)物，即使給活恐龍稱體重都是一個(gè)棘手的難題,，更別說(shuō)是利用恐龍化石來(lái)給它們稱體重,，現(xiàn)在這一難題得到解決。最近曼徹斯特大學(xué)古生物學(xué)和生物力學(xué)研究小組的卡爾·貝茨（Karl Bates）和他的同事們根據(jù)5個(gè)恐龍化石和2個(gè)霸王龍化石制作成恐龍復(fù)原模型,，使用激光成像技術(shù)測(cè)得洛磯山博物館的較小的霸王龍可能體重介于5.5和7噸之間,，而較大的可能重達(dá)8噸。
阿托卡高棘龍（Acrocanthosaurus atokensis）是一種大型肉食性恐龍,，模樣看起來(lái)像霸王龍,，但其背部的脊骨比霸王龍的大，而且較早出現(xiàn)在地球上,，大約出現(xiàn)在1.1億年前的白堊紀(jì)中期,。該研究小組稱高棘龍可能與MOR555型暴龍和中等身材的成年霸王龍?bào)w重相似，大約在6噸左右,。The Strutiomimum sedens,，它的名字意思是“鴕鳥龍”，也像霸王龍一樣生活在白堊紀(jì)中期,，體重大約在0.4—0.6噸之間,。
埃德蒙頓龍是鴨嘴龍科的一種。鴨嘴龍科（Hadrosauridae）是一群常見(jiàn)的草食性鳥腳類恐龍,，包括埃德蒙頓龍,、副櫛龍，它們發(fā)現(xiàn)于亞洲,、歐洲,、以及北美洲的下白堊紀(jì)地層。它們是上侏羅紀(jì),、下白堊紀(jì)禽龍類的后代,，并擁有類似的體型。根據(jù)埃德蒙頓龍的幼年標(biāo)本,，其體重達(dá)0.8—0.95噸,。作為成年龍，鴨嘴龍可長(zhǎng)到像霸王龍一樣大,。
該研究小組利用激光掃描（激光雷達(dá)）和計(jì)算機(jī)模擬方法,，創(chuàng)造了一系列三維模型標(biāo)本，試圖重塑與活恐龍相同的身形和大小的標(biāo)本,。這種激光掃描儀掃描全部安裝好的骨架,，制作出每根骨頭的空間位置和關(guān)節(jié)部位的三維模型,，這為我們提供了一個(gè)高清晰度的骨骼框架以及體腔模型，如胃,，肺和氣囊等內(nèi)部器官的再造,。這就得計(jì)算它的肌肉和內(nèi)臟的重量，所有這些信息都需要分析身體動(dòng)作,。
為了更準(zhǔn)確地測(cè)得每種恐龍的體重,，他們分析猜測(cè)每種器官以及每一部位的重量，以求準(zhǔn)確到與真實(shí)值相當(dāng),?？茖W(xué)家不能確定真實(shí)的恐龍有多胖，有多瘦,，身體上的脂肪應(yīng)當(dāng)有多少,，他們很有興趣知道恐龍的標(biāo)準(zhǔn)體重。他們認(rèn)為,，把體重估計(jì)得低一點(diǎn)最有可能是正確的,，因?yàn)榛畹目铸垥?huì)受呼吸作用、走路速度和體能消耗的影響,。
該研究小組還測(cè)量鴕鳥化石和活的鴕鳥的體重,，通過(guò)比較，得出測(cè)量技術(shù)的準(zhǔn)確性,。利用這些成果,，以進(jìn)一步探討運(yùn)動(dòng)的恐龍，尤其是他們是如何跑的,。
卡爾說(shuō)：“我們的技術(shù)使人們能夠想象活著的恐龍是胖是瘦,。當(dāng)你看到恐龍模型的骨骼，就可想象它的腹部有多大,。任何一個(gè)從5歲小孩到老教授的人看到模型都會(huì)說(shuō)：“我認(rèn)為這個(gè)再造恐龍?zhí)至嘶蛱萘恕?rdquo;他補(bǔ)充說(shuō)道：“這一研究幫助我們用三維的方式而不是用以前二維的方式了解恐龍是如何跑的,。”
再造更詳細(xì)的恐龍部位模型使我們能夠得知它們體重的變化情況，特別是它們?cè)谶M(jìn)化過(guò)程中質(zhì)心的改變,。我們都知道,，恐龍演變成鳥類，質(zhì)心變得靠近身體前部,，走路姿勢(shì)變得多種多樣,。雖然我們重造的恐龍不是鳥類的近親，但我們?nèi)阅芸吹綇陌⑼锌ǜ呒埖桨酝觚埖难葑冞^(guò)程中質(zhì)心在不斷向前靠,，非常接近現(xiàn)代鳥類的進(jìn)化圖,。（生物谷Bioon.com）
生物谷推薦原始出處：
PLoS ONE 4(2): e4532. doi:10.1371/journal.pone.0004532
Estimating Mass Properties of Dinosaurs Using Laser Imaging and 3D Computer Modelling
Karl T. Bates1*, Phillip L. Manning2,3, David Hodgetts3, William I. Sellers1
1 Adaptive Organismal Biology Research Group, Faculty of Life Sciences, University of Manchester, Jackson's Mill, Manchester, United Kingdom, 2 The Manchester Museum, University of Manchester, Manchester, United Kingdom, 3 School of Earth, Atmospheric and Environmental Science, University of Manchester, Manchester, United Kingdom
Abstract
Body mass reconstructions of extinct vertebrates are most robust when complete to near-complete skeletons allow the reconstruction of either physical or digital models. Digital models are most efficient in terms of time and cost, and provide the facility to infinitely modify model properties non-destructively, such that sensitivity analyses can be conducted to quantify the effect of the many unknown parameters involved in reconstructions of extinct animals. In this study we use laser scanning (LiDAR) and computer modelling methods to create a range of 3D mass models of five specimens of non-avian dinosaur; two near-complete specimens of Tyrannosaurus rex, the most complete specimens of Acrocanthosaurus atokensis and Strutiomimum sedens, and a near-complete skeleton of a sub-adult Edmontosaurus annectens. LiDAR scanning allows a full mounted skeleton to be imaged resulting in a detailed 3D model in which each bone retains its spatial position and articulation. This provides a high resolution skeletal framework around which the body cavity and internal organs such as lungs and air sacs can be reconstructed. This has allowed calculation of body segment masses, centres of mass and moments or inertia for each animal. However, any soft tissue reconstruction of an extinct taxon inevitably represents a best estimate model with an unknown level of accuracy. We have therefore conducted an extensive sensitivity analysis in which the volumes of body segments and respiratory organs were varied in an attempt to constrain the likely maximum plausible range of mass parameters for each animal. Our results provide wide ranges in actual mass and inertial values, emphasizing the high level of uncertainty inevitable in such reconstructions. However, our sensitivity analysis consistently places the centre of mass well below and in front of hip joint in each animal, regardless of the chosen combination of body and respiratory structure volumes. These results emphasize that future biomechanical assessments of extinct taxa should be preceded by a detailed investigation of the plausible range of mass properties, in which sensitivity analyses are used to identify a suite of possible values to be tested as inputs in analytical models.
