英國普茨茅斯大學(xué)的古生物學(xué)家Mark Witton博士通過對1.25億年前一塊飛翔爬行動物的頭骨化石進行研究,，發(fā)現(xiàn)它們可能為腐食動物——食性類似禿鷲,，它們以恐龍尸體為食。這塊翼龍頭骨化石保存于倫敦自然歷史博物館已長達一個世紀,，但直到現(xiàn)在Witton在研究中精確地重建了它的真實形貌后，才揭開了它的秘密,。相關(guān)研究3月21日在線發(fā)表于《公共科學(xué)圖書館—綜合》
Witton專門研究翼龍——一類飛翔于恐龍時代天空中的巨型帶翅膀的爬行動物,。在最近一次瀏覽博物館的時候，他意識到這塊頭骨可能是頭骨組合中極為重要的一塊,。這副聞名的闊齒帆翼龍（Istiodactylus latidens）頭骨化石由兩部分組成,，分別是腦殼（braincase）和鄂部尖端（jaw tip）,，但它還存在常被忽略的第三部分——將前兩者連起來的一個結(jié)構(gòu),。長達100年內(nèi)，闊齒帆翼龍都被認為頭骨長約半米,，但與身體的精確比例卻仍不清楚,，因為僅有部分頭骨骨骼被研究過。Witton認為,，新發(fā)現(xiàn)的第三部分對于揭示闊齒帆翼龍頭部的信息極為重要,，同時它也能將之前研究過的牙齒化石聯(lián)系起來，它為研究闊齒帆翼龍的食譜和取食習(xí)性提供了新資料,。
Witton說，帆翼龍是一類擁有極為特殊的刀面切齒的生物,，因此之前就有人認為它們應(yīng)該是食腐的,，但相應(yīng)的頭骨證據(jù)卻一直未出現(xiàn)。這塊碎片表明帆翼龍頭骨比預(yù)想的要短20%,，它的頭骨非常短,、寬且長，這是研究者未曾預(yù)料到的,。Witton說,，只有擁有發(fā)現(xiàn)之眼的人,，才會在老化石中發(fā)現(xiàn)新訊息,。在倫敦自然歷史博物館珍藏著數(shù)量眾多的翼龍化石寶藏,。因此長期以來，與翼龍相關(guān)研究的價值在這里都被低估,，或許只有遇到真正的“伯樂”,，它們才會煥發(fā)出光彩。
第三塊碎片顯示,，帆翼龍的臉頰骨非常柔軟,，僅有6毫米長，而整個頭骨可長達450毫米,，因此要發(fā)現(xiàn)這塊碎骨需要非常細心。現(xiàn)代食腐鳥類中擁有相似的結(jié)構(gòu),，頭骨包括極硬與極軟的部分,，由于它們可以輕易且完全地控制已死去的獵物，因此極軟部分可以在頭骨中存在，因為它們不用擔(dān)心它會被弄碎,。同時,，由于食腐鳥類需要用力拖拽尸體，因此它們的面部骨骼錨定了大量的脖頸肌肉,。這塊帆翼龍化石于1904年發(fā)現(xiàn)于懷特島，1911年收藏于倫敦自然歷史博物館,。（生物谷 bioon.com）
doi:10.1371/journal.pone.0033170
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New Insights into the Skull of Istiodactylus latidens (Ornithocheiroidea, Pterodactyloidea)
Mark P. Witton
The skull of the Cretaceous pterosaur Istiodactylus latidens, a historically important species best known for its broad muzzle of interlocking, lancet-shaped teeth, is almost completely known from the broken remains of several individuals, but the length of its jaws remains elusive. Estimates of I. latidens jaw length have been exclusively based on the incomplete skull of NHMUK R3877 and, perhaps erroneously, reconstructed by assuming continuation of its broken skull pieces as preserved in situ. Here, an overlooked jaw fragment of NHMUK R3877 is redescribed and used to revise the skull reconstruction of I. latidens. The new reconstruction suggests a much shorter skull than previously supposed, along with a relatively tall orbital region and proportionally slender maxilla, a feature documented in the early 20th century but ignored by all skull reconstructions of this species. These features indicate that the skull of I. latidens is particularly distinctive amongst istiodactylids and suggests greater disparity between I. latidens and I. sinensis than previously appreciated. A cladistic analysis of istiodactylid pterosaurs incorporating new predicted I. latidens skull metrics suggests Istiodactylidae is constrained to five species (Liaoxipterus brachyognathus, Lonchengpterus zhoai, Nurhachius ignaciobritoi, Istiodactylus latidens and Istiodactylus sinensis) defined by their distinctive dentition, but excludes the putative istiodactylids Haopterus gracilis and Hongshanopterus lacustris. Istiodactylus latidens, I. sinensis and Li. brachyognathus form an unresolved clade of derived istiodactylids, and the similarity of comparable remains of I. sinensis and Li. brachyognathus suggest further work into their taxonomy and classification is required. The new skull model of I. latidens agrees with the scavenging habits proposed for these pterosaurs, with much of their cranial anatomy converging on that of habitually scavenging birds.
