據(jù)國外媒體報道,，目前,，考古學(xué)家最新研究揭開了與恐龍同時期存在爬行動物恩吐龍(aetosaurs)物種的真實面目，他們依據(jù)這些物種化石證據(jù)分析其行為特征頗似鱷魚、母牛和犰狳的混合體,，同時,，他們發(fā)現(xiàn)在其泄殖腔附近環(huán)繞著鋒利的刺狀突起，它們?nèi)绾芜M(jìn)行交配生殖仍是一個謎團(tuán),。
這項發(fā)現(xiàn)發(fā)表在近期出版的《脊椎動物古生物學(xué)期刊》（Journal of Vertebrate Paleontology）中,，特別是恩吐龍物種中的正體龍(Typothorax)，它是恐龍成為地球霸主之前較大的食草動物之一,。它是2.3億-2億年前一種8英尺長,、225磅重的爬行動物，它們的身體上覆蓋著重厚的甲層和鋒利的刺狀突起,。美國新墨西哥國家歷史科學(xué)博物館的馬修·塞倫斯基說：“考古學(xué)家曾挖掘發(fā)現(xiàn)三疊紀(jì)末期的多數(shù)恐龍物種,，比如：像火雞般大小的腔骨龍，它們太過于瘦脊,，難以對覆蓋厚甲的正體龍構(gòu)成威脅,。”
塞倫斯基解釋稱，現(xiàn)已滅絕的恩吐龍之后進(jìn)化為兩個分支：恐龍和近親物種,，鱷魚的祖先和近親物種,。而正體龍正是后一個分支。
近期,，兩位考古學(xué)家在美國新墨西哥州荒原上發(fā)現(xiàn)兩具正體龍骨骼殘骸,，他們分析顯示正體龍從頭部至腳趾都覆蓋著堅硬的甲層。期間他們獲得一項驚人發(fā)現(xiàn),，鋒利的刺狀突起環(huán)繞在泄殖腔(這一生理結(jié)構(gòu)包括腸道,、生殖器和泌尿道)。
令考古學(xué)家置疑的是正體龍如何進(jìn)行交配,？塞倫斯基稱,，我們并不知道這些環(huán)繞在泄殖腔周圍鋒利的刺狀突起如何影響交配行為，盡管我們確信這兩只正體龍可實現(xiàn)正常交配繁殖,。
通過分析兩具正體龍骨骼,，考古學(xué)家發(fā)現(xiàn)這種爬行動物長著短而粗的脖頸，鈍狀鼻頭和小型葉狀牙齒,。前肢可伸展,，后肢較大且直立。美國阿巴拉契亞大學(xué)地質(zhì)教授安迪·?？颂胤Q,，正體龍主要的掠食對象可能是半水棲植龍。(生物谷Bioon.com)
生物谷推薦原文出處：
Journal of Vertebrate Paleontology DOI: 10.1080/02724631003763524
Articulated skeletons of the aetosaur Typothorax coccinarum Cope (Archosauria: Stagonolepididae) from the Upper Triassic Bull Canyon Formation (Revueltian: early-mid Norian), eastern New Mexico, USA
Andrew B. Heckert a; Spencer G. Lucas b; Larry F. Rinehart b; Matthew D. Celeskey b; Justin A. Spielmann b;Adrian P. Hunt b
a Department of Geology, Appalachian State University, Boone, North Carolina, U.S.A.
b New Mexico Museum of Natural History and Science, Albuquerque, New Mexico, U.S.A.
We report two nearly complete, articulated skeletons of the crurotarsan archosaur Typothorax coccinarum from the Upper Triassic Bull Canyon Formation of east-central New Mexico. These are the most complete, articulated aetosaurs from North America and provide a wealth of new anatomical and paleobiological data, including articulated presacral armor that confirms the distinctiveness of T. coccinarum from the closely related T. antiquum and from Redondasuchus. Cervical vertebrae are small, but the corresponding reduction in armor is accomplished by a reduced number of cervical osteoderms. The third row of osteoderms includes a thin, elongate, lateral spike. The ventral armor consists of 10 thoracic columns and four caudal columns of osteoderms. Spiked osteoderms near the cloacal vent are the first spikes reported in aetosaurian ventral osteoderms. The forelimb of T. coccinarum was very short, only ～0.65 the length of the hind limb, possesses some adaptations found in digging taxa, and was held in a sprawling or 'semi-erect' position. In contrast the hind limb is much more robust, 'pillar erect,' and functionally mesotarsal. The articulated pes, including unguals, has, minimally, the phalangeal formula 2-3-3?-4?-3? with relative digit lengths III > II > IV > I > V, digits I-IV equally as wide as long and other characteristics of the footprint ichnogenus Brachychirotherium, often attributed to an aetosaurian trackmaker. Both specimens are ～2.5 m long and the preserved armor and limb bones are as large or larger than known Typothorax fossils, suggesting that this approximates the upper size limit of T. coccinarum, and we calculate body mass estimates of ～100-104 kg for both specimens.
