新种―振元翼龙（Zhenyuanopterus）

化石情缘

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新种―振元翼龙（Zhenyuanopterus）

    笔者有幸见到 新命名的振元翼龙 ，并拍了照片，介绍给网友共享。
    振元翼龙（属名：Zhenyuanopterus）是翼龙目北方翼龙科的一属，化石发现于中国辽宁省的义县组，地质年代约白垩纪早期的阿普第阶早期。

- Y; u4 K) ^% @5 L4 E  c参考资料 振元翼龙化石时期： 白垩纪早期

科学分类

界： 动物界 Animalia 门： 脊索动物门 Chordata 纲： 蜥形纲 Sauropsida 目： 翼龙目 Pterosauria 亚目： 翼手龙亚目 Pterodactyloidea 总科： 鸟掌翼龙超科 Ornithocheiroidea 科： 北方翼龙科 Boreopteridae 属： 振元翼龙属 Zhenyuanopterus * w: q" ?+ l7 M( a. n: S$ h: B

        种     长吻振元翼龙 Z. longirostris (模式种)

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化石情缘

新种―振元翼龙（Zhenyuanopterus）

      发现于义县组，Zhenyuanopterus longirostris翼展达4米，它有很多牙齿，可能用来捕鱼。

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化石情缘

新种―振元翼龙（Zhenyuanopterus）
) V. O2 V* {3 B& w2 B; J) W古生态学

振元翼龙的化石都发现于中国辽宁省的义县组，该地层过去是个多湖泊的地区，这些翼龙类生存于接邻淡水的环境。振元翼龙可能飞行于水面上，用针状牙齿捕抓接近水面的鱼类。某些现代鸟类也有类似的猎食模式。

    有研究人员提出，振元翼龙可能是其近亲北方翼龙的成年个体标本；北方翼龙目前只有发现幼年个体标本 。
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化石情缘

新种―振元翼龙（Zhenyuanopterus）
参考资料

) f1 D# R% U: Q) B" B+ f$ WChapter 17. Boreopteridae
1 o# v; z0 R% u1 w4 h7 p& N8 GPTEROSAURIA > MONOFENESTRATA > PTERODACTYLOIDEA > ORNITHOCHEIROIDEA > BOREOPTERIDAE
By now, I’m sure we’re all becoming accustomed to how downright weird pterosaurs look. Even the boring ones have natty looking teeth and preposterous bodily proportions, while more extreme variants wouldn’t look out of place in a Guillermo del Toro movie. The bizarre appearances of even these have been superseded by a newly discovered pterosaur clade, however, pterosaurs with chunky-looking headcrests, enormously long jaws and ridiculous numbers of teeth so long that they project way beyond the bounds of the upper and lower jaws. These critters are the boreopterids (Fig. 17.1), a group thus far known exclusively from the Barremian/Aptian (125 million years ago) of northern China that became known to palaeontologists as recently as 2005 (Lü and Ji 2005). To date, only two definitively-identified boreopterid specimens have been found but, happily, these specimens are complete enough that most of their anatomy is already well known.
- P# E$ y% e7 E5 {Boreopterids have generally been placed within Ornithocheiroidea (Lü and Ji 2005, Unwin 2005; Lü et al. 2006b, 2008a, 2010a), although Andres and Ji (2008) suggested they may have affinities to ctenochasmatoids (Chapter 19). My money is firmly with the ornithocheiroid guys in this case: while the skulls of boreopterids are a little ctenochasmatoid-esque, their postcranial skeletons are almost identical to those of ornithocheiroids, with particular similarities to members of Ornithocheiridae (Chapter 16). Indeed, I reckon some bones of the boreopterid skeleton are so ornithocheirid-like (e.g. their humeri) that we may need to be a little cautious about the identity of some isolated so-called ‘ornithocheirid’ limb bones: they may, in fact, represent boreopterids. In addition, they also have ridiculously small feet like those seen in the istiodactylid ornithocheiroids (Chapter 15), a stark contrast to the massive, wading feet of many ctenochasmatoid species.
Presently, boreopterids have only been identified from one stratigraphic unit: China’s Lower Cretaceous Yixian Formation (Fig. 17.2). The first of their fossils was unveiled in 2005 when the skeleton of a virtually complete, if somewhat imperfect, and rather immature individual was described (Lü and Ji 2005) and named Boreopterus cuiae. Its genus name translates to ‘northern wing’, a reference to the specimen’s provenance to northern China. Lü and Ji thought that the tooth morphology of Boreopterus suggested affinities to Ornithocheiridae, a finding generally agreed with by Unwin (2006) and Lü et al. (2006b, 2008a, 2010a; but also see Andres and Ji 2008). Boreopterus became the namesake of Boreopteridae, a distinct clade of ornithocheiroids, when Lü et al. (2006b) considered it to form a clade with another Chinese pterodactyloid, Feilongus (see below and Chapter 19).

化石情缘

The second boreopterid specimen, named Zhenyuanopterus longirostris, presented a substantially better preserved skeleton that really waves away any ideas of housing boreopterids outside of Ornithocheiroidea (Lü 2010). The preservation of the only known specimen of Zhenyuanopterus is exceptional (Fig. 17.3), especially for such a large pterosaur (3.5 m span). Barely a bone is out of place and, though somewhat squashed, almost every component of the skeleton can be observed in detail. Happily, the sole-known Zhenyuanopterus is also more osteologically mature than Boreopterus, giving us a good idea what adult boreopterids look like. There is a good chance that both Zhenyuanopterus and Boreopterus are actually the same species, with the former merely being a subadult version of the latter. Most of the differences between them (e.g. size, presence of a headcrest, number of teeth) can be explained as effects of age, and their occurrence in the same beds heightens the possibility further.
One animal that is definitely distinct from Boreopterus, however, is a third alleged boreopterid genus – Feilongus. Roped into Boreopteridae by Lü et al. (2006b) and Lü (2010), this animal is only from a skull and some unpublished remains and, it must be said, looks a bit awkward in a boreopterid line-up. Sure, it has the long rostrum and needle-like teeth like of boreopterids, but the number and distribution of teeth, nature of its headcrest, inclination of its posterior skull bones and elongate cervicals are more in like those of ctenochasmatoids (Wang et al. 2005, 2009; Andres et al. 2008). Hence, my bet is that Feilongus lies amongst them rather than the boreopterids, and we’ll catch up with it again Chapter 19.
Anatomy
Boreopterid anatomy (Fig. 17.4) is unusually well-known for such a new pterosaur group, with descriptions of most bones from the two recognised boreopterid taxa given by Lü and Ji (2005), Lü et al. (2006b) and Lü (2010). These forms are notably smaller than other ornithocheiroids: Boreopterus has a wingspan of 1.9 m, while Zhenyuanopterus spans 3.5 m. As noted above, neither of these specimens represent fully-grown individuals, with Boreopterus known from an especially young, osteologically-immature animal. The Zhenyuanopterus specimen, by contrast, has begun to form a notarium and fuse its skull bones, suggesting it had almost finished its growing and wouldn’t get much bigger (as per pterosaur skeletal maturity criteria set by Bennett [1993]). It remains to be seen whether other boreopterid taxa grew to larger sizes.
Boreopterid skulls are their most striking and defining feature (Fig. 17.3B). Like those of most other ornithocheiroids, they are proportionally large (twice the length of the torso) with particularly long rostra that occupies over two-thirds of the skull length. Zhenyuanopterus possess a large crest that erupts from the skull at its midlength to extend along the skull until the level with the posterior region of the nasoantorbital fenestra, and another small crest is found at the back of the skull. Boreopterus lacks both of these features, but the immaturity of the specimen suggests crest development may not have begun in this individual yet. The temporal openings and orbits are small compared to those seen in ornithocheirids, suggesting the eyes and jaw muscles weren’t huge. Their mandibles are long, un-crested and fused along the anterior two-thirds of their length. Both the upper and lower jaws are brimming with equal numbers of teeth that occupy most of the jaw length. Boreopterus packs almost 60 teeth into each jaw (116 in total) while Zhenyuanopterus squeezes in 92 into the same space (184 in total). The teeth are particularly long and slender, being 10 times their width with a slight posterior curve. Unlike all other pterosaurs, the teeth are long enough that they extend well above and below the opposing jaw bones. The longest teeth are found at the jaw tips with steady reductions in tooth size posteriorly until, at the back of the mouth, they’re a mere tenth of the length of those at the front.
* y; F, T, l: L7 A! e( LMuch of the postcranial skeleton of boreopterids is like that seen in ornithocheirids. The cervical series is long compared to the torso with particularly large, rounded neural spines. 12 dorsals are preserved in Zhenyuanopterus, three of which have fused into the beginnings of a notarium. The sacrum comprises 4 vertebrae and the tail is comprised of at least 13 elongate caudals. This has resulted in boreopterids possessing tails that are amongst the longest of all pterodactyloids, a feature that they share with another ornithocheiroid group, the pteranodontians (Chapter 18).

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Boreopterid forelimbs are overdeveloped in the manner typical of ornithocheiroids and, with the exception of the wing finger, they are proportionally very similar to those of ornithocheirids. The scapulocoracoids are reinforced, blocky and large, anchoring onto broad sterna with pronounced cristospines. Their humeri possess elongate, warped deltopectoral crests and stout shafts. The radius and ulna are similarly both robust and around a third longer than the humerus, but the carpals are poorly known thanks to poor preservation and incomplete fusion. The pteroid is relatively slender and around 40 per cent of the forearm length. It isn’t clear if, as in ornithocheirids, some of the metacarpals had lost contact with the carpals as this region is obscured in both known boreopterid specimens. Their wing fingers are proportionally more like that of istiodactylids than ornithocheirids, occupying half of the wing length compared to the 60 per cent seen in ornithocheirids. Their non-flight fingers are small but capped with relatively robust claws. Boreopterid pelvic girdles are poorly known, but their hindlimbs are very diminutive. They are generally similar in length and proportions to those of ornithocheirids, but boreopterid feet are seriously titchy, their maximum length being an embarrassing 10 per cent of total leg length. Locomotion " t3 Z! k3 f1 C6 kWith perhaps one tiny exception, diddly-squat has been said in print about the biomechanics and functional biology of boreopterids, including their locomotory abilities. Their proportional similarity to ornithocheirids suggests that some generalities about ornithocheirid locomotion will fit boreopterids nicely, however. For instance, the elongate, warped deltopectoral crest and reinforced scapulae that we see in boreopterids probably signifies frequent launching from deep water, just as it does in ornithocheirids (Habib and Cunningham 2010). Similarly, the tiny hindlimbs of boreopterids dictate that their wings bore a correspondingly narrow chord. Their shorter wing fingers would make the wing somewhat shorter and lower aspect than those of ornithocheirids, however, possibly reflecting a preference for inland habits where short wings are beneficial for takeoff (Rayner 1988). The finding of all (two) boreopterid specimens in a freshwater deposit ties in nicely with this idea, but, of course, a much larger sample size is needed to ascertain a depositional bias in the boreopterid record. The miniscule feet of boreopterids suggest that they didn’t worry too much about moving around on the ground, and their heavily-skewed limb proportions would have probably limited them to shuffling or bounding around in the fashion we described for ornithocheirids in the previous chapter. We may assume, given their apparent adaptations for taking off from water, that they were at least stable when swimming or floating and, indeed, their probable adaptations for aquatic feeding suggest they should be at home in aquatic settings. Palaeoecology   W1 X% |% g/ ~, [+ o" q" M8 {# pThe only comments about boreopterid dietary preferences I know of stem from Wang and Zhou (2006), who suggested that boreopterids habitually dined on fish. This makes some sense: the elongate jaws and necks of boreopterids are well suited to being plunged into deep into water to gather fish or other nektonic critters, but exactly how they would’ve apprehended their prey hasn’t been established. Boreopterid teeth are the sticking point as they look so slender and delicate that it’s easy to imagine feisty prey damaging their teeth without too much hassle. Their eyes, too, are pretty tiny, which doesn’t really suit a predator out to spot prey from a distance. As a consequence, boreopterids may have been restricted to using their jaws as a cage to trap numerous, small swimming critters in one go. The close spacing and extremely long nature of their teeth is certainly consistent with this, and we can imagine boreopterids combing the water for food before lifting their heads to strain consumables from the water through their tightly-packed teeth. They seem to possess the necks necessary for this task, too, with the large and complex nature of their cervical vertebrae indicating a powerfully muscled neck. This doesn’t sound a million miles away from the dabbling that we see in modern ducks and geese, but boreopterids would be ill-suited to surviving on the types of vegetative matter that these birds eat: their torsos are not large enough house large, plant-digesting guts for that task. Such a foraging strategy would probably require the feeding boreopterid to alight on the water surface or stand in shallow water to be successful, but this brings their stunted feet and hindlimbs into question. Perhaps they preferred rather still waters where they didn’t need large, flipper-like feet to punt themselves around or, maybe they were able to use their forelimbs to shunt themselves about while their bodies were buoyed up by water. This new clade of pterosaurs clearly has a lot left to tell, then, and we can only hope that new discoveries revealing more details of their evolutionary history and distribution are not too far away. Hopefully, in years to come they will be as well documented as the next group we’re going to meet: known from well over 1000 specimens and the subject of study for almost 150 years, they can boast numerous bone-by-bone monographic descriptions and buttloads of research into all manners of their palaeobiology. They are also the last clade of ornithocheiroids on our tour and, with their iconic skulls shapes, are perhaps the most famous pterosaurs in the world. Next stop, then, the Pteranodontia. * s/ a5 g/ s1 t+ O1 e   ?- R# w' y1 f( q, R' l8 U 0 H5 N4 u; t8 ?4 o% P) k

男子汉wangwuyi

谢谢分享

如月中天

太棒了！让人看了痛不欲生的感觉！

科普化石

是 孙振元

化石情缘

科普化石 发表于 2012-6-10 19:46
是 孙振元

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tguqr

不错的贴，太喜欢了，大家都顶啊