Basal dinosauriform and theropod dinosaurs from the middle-late Norian (Late Triassic) of Poland: implications for Triassic dinosaur evolution and distribution

The rise of dinosaurs during the Triassic is a widely studied evolutionary radiation, but there are still many unanswered questions about early dinosaur evolution and biogeography that are hampered by an unevenly sampled Late Triassic fossil record. Although very common in western North America and parts of South America, dinosaur (and more basal dinosauriform) remains are relatively rare in the Upper Triassic deposits of Europe, making any new discoveries critically important. One of the most diverse dinosauriform assemblages from Europe comes from the Poręba site in Poland, a recently described locality with exposures of the Zbąszynek Beds, which have a palynomorph assemblage characteristic for the mid–late Norian in the biostratigraphic schemes of the Germanic Basin. Using a synapomorphy-based approach, we evaluate several isolated dinosauriform specimens from Poręba. This assemblage includes a silesaurid, a herrerasaurid and remains of another type of theropod (potentially a neother...

三叠纪时期恐龙的崛起是广受学界关注的演化辐射（evolutionary radiation）事件，但晚三叠世化石记录采样不均的现状，仍制约着学界对早期恐龙演化与生物地理学诸多未解问题的研究。尽管恐龙及更基干的恐龙形类（dinosauriform）化石在北美西部与南美部分地区分布广泛，但欧洲上三叠统（Upper Triassic）地层中该类化石遗存相对稀少，因此任何新发现都具有至关重要的科研价值。欧洲已知多样性最高的恐龙形类组合之一，产自波兰的波列巴（Poręba）遗址——这是一处近年被正式记述的露头点，出露兹巴申克（Zbąszynek）组地层；该地层的孢粉组合（palynomorph assemblage）特征，契合日耳曼盆地（Germanic Basin）生物地层学（biostratigraphic）方案中的中-晚诺利阶（Norian）特征。本研究采用基于共有衍征（synapomorphy）的分析方法，对波列巴遗址出土的多件孤立恐龙形类标本开展系统厘定。该化石组合包含1种西里龙科（silesaurid）、1种艾雷拉龙科（herrerasaurid），以及另一类兽脚类（theropod，可能为新兽脚类……）的化石遗存。