ブラキオサウルス

📖 1. 概要

後ろ脚よりも前脚の方が長く、頭の高さが13m（マンションの4～5階建て相当）に達したジュラ紀を代表する巨大竜脚類です。

🌐 Wikipedia 要約抜粋

Brachiosaurus is a genus of sauropod dinosaur that lived in North America during the Late Jurassic, about 155.6 to 145.5 million years ago. It was first described by American paleontologist Elmer S. Riggs in 1903 from fossils found in the Colorado River valley in western Colorado, United States. Riggs named the dinosaur Brachiosaurus altithorax; the generic name is Greek for "arm lizard", in reference to its proportionately long arms, and the specific name means "deep chest". Brachiosaurus is estimated to have been between 18 and 22 meters long; body mass estimates of the subadult holotype specimen range from 28.3 to 46.9 metric tons. It had a disproportionately long neck, small skull, and large overall size, all of which are typical for sauropods. Atypically, Brachiosaurus had longer forelimbs than hindlimbs, which resulted in a steeply inclined trunk and a proportionally shorter tail.

🦴 2. 体の構造と特徴

頸椎と背椎の内部に気嚢（Air sac）とつながった含気性の空洞が発達し、骨の重さを減らすとともに呼吸効率を最大化していました。

🔍 3. 化石記録と古生態

1日に数百kgの針葉樹の葉を摂取しながらジュラ紀の平原を歩いていました。

🇰🇷 4. 韓国との関わり

朝鮮半島の固城・海南・義城で発見される巨大竜脚類の足跡化石の主たちと同じ系統です。