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A specimen of Paralycoptera Chang & Chou 1977 (Teleostei: Osteoglossoidei) from Hong Kong (China) with a potential Late Jurassic age that extends the temporal and geographical range of the genus.

Tse TK, Pittman M, Chang MM - PeerJ (2015)

Bottom Line: However, spores found in the Formation suggest an Early Cretaceous age that is consistent with the existing age assignment to Paralycoptera.We argue that the proposed temporal range extension is genuine because it is based on recent high precision radiometric age data, but given the discrepancies with the biostratigraphic ages further investigation is needed to confirm this.This study provides an important step towards revealing Hong Kong's Mesozoic vertebrate fauna and understanding its relationship to well-studied mainland Chinese ones.

View Article: PubMed Central - HTML - PubMed

Affiliation: Vertebrate Palaeontology Laboratory, Life and Planetary Evolution Research Group, Department of Earth Sciences, The University of Hong Kong , Pokfulam, Hong Kong , China.

ABSTRACT
We describe a Mesozoic fish Paralycoptera sp. (Teleostei: Osteoglossoidei), on the basis of a postcranial skeleton collected from the volcaniclastic mudstones of the Lai Chi Chong Formation of Hong Kong, China. The new finding-representing the city's first Mesozoic fish-extends the geographical distribution of Paralycoptera from eastern mainland China into Hong Kong, demonstrating a wider distribution than previously appreciated for this genus. A radiometric age for the Lai Chi Chong Formation of 146.6 ± 0.2 Ma implies a temporal range expansion for Paralycoptera of approximately 40 million years back from the Early Cretaceous (∼110 Ma). However, spores found in the Formation suggest an Early Cretaceous age that is consistent with the existing age assignment to Paralycoptera. We argue that the proposed temporal range extension is genuine because it is based on recent high precision radiometric age data, but given the discrepancies with the biostratigraphic ages further investigation is needed to confirm this. This study provides an important step towards revealing Hong Kong's Mesozoic vertebrate fauna and understanding its relationship to well-studied mainland Chinese ones.

No MeSH data available.


Skeletal reconstruction of Paralycoptera.Reconstructed skeleton of Paralycoptera (Xu & Chang, 2009; used with the permission of the authors).
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fig-7: Skeletal reconstruction of Paralycoptera.Reconstructed skeleton of Paralycoptera (Xu & Chang, 2009; used with the permission of the authors).

Mentions: In comparing SHGM L275 and Paralycoptera based on the above analyses (Table 1 and S2–S5), there were a few character state discrepancies. These unmatched characters include: (1) the condition of the neural spine on ural centrum 1—whether the neural spine is complete or rudimentary, and (2) the number of epurals. According to Wilson & Murray (2008), the neural spine on the first ural centrum of Paralycoptera should be absent or rudimentary, whereas Shen (1996) and Xu & Chang (2009) observe a completely developed neural spine. Zhang (2006) is uncertain about the relative development of this spine, but in SHGM L275 a rudimentary neural spine is present. The number of epurals present in Paralycoptera remains controversial. Shen (1996) identified a single epural in Paralycoptera whereas Xu & Chang (2009) noted its absence. In specimens IVPP V2989.65, .100 and .105 of Paralycoptera, we also identified no epurals, like Xu & Chang (2009). An ‘x’ has been marked in Table 1 for this character, even though the character state used by Xu & Chang (2009)—‘one or absent’—should justify the use of a ‘○’ mark instead. We therefore advocate the separation of this state in future work in accordance with Greenwood (1970) and the epural characters of Shen (1996), Zhang (2006) and Wilson & Murray (2008). There is a possible epural in SHGM L275. Zhang (2006) and Wilson & Murray (2008) both record uncertainty in the number of epurals in Paralycoptera. The first preural centrum of SHGM L275 has a complete neural spine, as identified in Paralycoptera by all four aforementioned analyses, but Xu & Chang (2009) mistakenly recorded a ‘rudimentary or absent’ neural spine in their data matrix. Excluding the aforementioned discrepancies, the four studies otherwise converge on SHGM L275 being a specimen of Paralycoptera. However, Xu & Chang’s (2009) observations of individual anatomical variation within Paralycoptera actually explain the differences in the caudal skeleton observed by Shen (1996), Zhang (2006) and Wilson & Murray (2008). Therefore, this confirms that SHGM L275 is a specimen of Paralycoptera (Fig. 7), which in our opinion negates the need for a numerical phylogenetic analysis. Xu & Chang (2009) synonymised the genus into one species P. wui whose features in SHGM L275 are:


A specimen of Paralycoptera Chang & Chou 1977 (Teleostei: Osteoglossoidei) from Hong Kong (China) with a potential Late Jurassic age that extends the temporal and geographical range of the genus.

Tse TK, Pittman M, Chang MM - PeerJ (2015)

Skeletal reconstruction of Paralycoptera.Reconstructed skeleton of Paralycoptera (Xu & Chang, 2009; used with the permission of the authors).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4380157&req=5

fig-7: Skeletal reconstruction of Paralycoptera.Reconstructed skeleton of Paralycoptera (Xu & Chang, 2009; used with the permission of the authors).
Mentions: In comparing SHGM L275 and Paralycoptera based on the above analyses (Table 1 and S2–S5), there were a few character state discrepancies. These unmatched characters include: (1) the condition of the neural spine on ural centrum 1—whether the neural spine is complete or rudimentary, and (2) the number of epurals. According to Wilson & Murray (2008), the neural spine on the first ural centrum of Paralycoptera should be absent or rudimentary, whereas Shen (1996) and Xu & Chang (2009) observe a completely developed neural spine. Zhang (2006) is uncertain about the relative development of this spine, but in SHGM L275 a rudimentary neural spine is present. The number of epurals present in Paralycoptera remains controversial. Shen (1996) identified a single epural in Paralycoptera whereas Xu & Chang (2009) noted its absence. In specimens IVPP V2989.65, .100 and .105 of Paralycoptera, we also identified no epurals, like Xu & Chang (2009). An ‘x’ has been marked in Table 1 for this character, even though the character state used by Xu & Chang (2009)—‘one or absent’—should justify the use of a ‘○’ mark instead. We therefore advocate the separation of this state in future work in accordance with Greenwood (1970) and the epural characters of Shen (1996), Zhang (2006) and Wilson & Murray (2008). There is a possible epural in SHGM L275. Zhang (2006) and Wilson & Murray (2008) both record uncertainty in the number of epurals in Paralycoptera. The first preural centrum of SHGM L275 has a complete neural spine, as identified in Paralycoptera by all four aforementioned analyses, but Xu & Chang (2009) mistakenly recorded a ‘rudimentary or absent’ neural spine in their data matrix. Excluding the aforementioned discrepancies, the four studies otherwise converge on SHGM L275 being a specimen of Paralycoptera. However, Xu & Chang’s (2009) observations of individual anatomical variation within Paralycoptera actually explain the differences in the caudal skeleton observed by Shen (1996), Zhang (2006) and Wilson & Murray (2008). Therefore, this confirms that SHGM L275 is a specimen of Paralycoptera (Fig. 7), which in our opinion negates the need for a numerical phylogenetic analysis. Xu & Chang (2009) synonymised the genus into one species P. wui whose features in SHGM L275 are:

Bottom Line: However, spores found in the Formation suggest an Early Cretaceous age that is consistent with the existing age assignment to Paralycoptera.We argue that the proposed temporal range extension is genuine because it is based on recent high precision radiometric age data, but given the discrepancies with the biostratigraphic ages further investigation is needed to confirm this.This study provides an important step towards revealing Hong Kong's Mesozoic vertebrate fauna and understanding its relationship to well-studied mainland Chinese ones.

View Article: PubMed Central - HTML - PubMed

Affiliation: Vertebrate Palaeontology Laboratory, Life and Planetary Evolution Research Group, Department of Earth Sciences, The University of Hong Kong , Pokfulam, Hong Kong , China.

ABSTRACT
We describe a Mesozoic fish Paralycoptera sp. (Teleostei: Osteoglossoidei), on the basis of a postcranial skeleton collected from the volcaniclastic mudstones of the Lai Chi Chong Formation of Hong Kong, China. The new finding-representing the city's first Mesozoic fish-extends the geographical distribution of Paralycoptera from eastern mainland China into Hong Kong, demonstrating a wider distribution than previously appreciated for this genus. A radiometric age for the Lai Chi Chong Formation of 146.6 ± 0.2 Ma implies a temporal range expansion for Paralycoptera of approximately 40 million years back from the Early Cretaceous (∼110 Ma). However, spores found in the Formation suggest an Early Cretaceous age that is consistent with the existing age assignment to Paralycoptera. We argue that the proposed temporal range extension is genuine because it is based on recent high precision radiometric age data, but given the discrepancies with the biostratigraphic ages further investigation is needed to confirm this. This study provides an important step towards revealing Hong Kong's Mesozoic vertebrate fauna and understanding its relationship to well-studied mainland Chinese ones.

No MeSH data available.