Lower Cambrian helcionelloid macromolluscs from South Australia

Jacquet, Sarah; Brock, Glenn A.

doi:10.1016/j.gr.2015.06.012

Cited by 32 publications

(23 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…). Although steinkerns retain information as imprints on the internal surface of the shell, information on the exterior is often lost, severely limiting the ability to designate and identify species (Skovsted , Jacquet & Brock ).…”

Section: Features Of Mackinnonia Comparing M Rostrata Specimens Fromentioning

confidence: 99%

Morphometric analysis of inter‐ and intraspecific variation in the Cambrian helcionelloid mollusc Mackinnonia

Jackson

Claybourn

2018

Palaeontology

View full text Add to dashboard Cite

Phylogenetic relationships within the helcionelloid molluscs have been difficult to establish. One of the reasons for this is that qualitative approaches to investigating morphological variation in this group have struggled to identify clear patterns. An alternative method of identifying these patterns is to study these organisms quantitatively. Here this approach is exemplified by employing morphometric methods to investigate patterns of subtle morphological variation in two species of Mackinnonia Runnegar in Bengtson et al. from Cambrian Series 2, Stages 3–4. Specifically, a combination of elliptical Fourier and multivariate analyses were conducted to study intra‐ and interspecific variation in protoconch form as well as variation in ontogenetic trajectory of the teleoconch of two species of Mackinnonia. The material used consists of two assemblages of Mackinnonia rostrata (Zhou & Xiao), from the Shackleton Limestone of Antarctica and Ajax Limestone of Australia, and an assemblage of Mackinnonia taconica (Landing & Bartowski) from the Bastion Formation of Greenland. Results of this study show significant (p < 0.0001) differences in protoconch shape between all three groups. Ontogenetic sequences of outline curves truncated at successive rugae significantly (p < 0.05) discriminate between M. rostrata and M. taconica. These techniques uncovered significant intraspecific morphological variation of disparate assemblages of M. rostrata despite shared qualitative features and structure a conceptual framework for understanding such patterns of variation and put this in the context of the incipient species concept.

show abstract

Section: Features Of Mackinnonia Comparing M Rostrata Specimens Fromentioning

confidence: 99%

Morphometric analysis of inter‐ and intraspecific variation in the Cambrian helcionelloid mollusc Mackinnonia

Jackson

Claybourn

2018

Palaeontology

View full text Add to dashboard Cite

show abstract

“…Examples of this, among others, include polygonal imprints that are interpreted as calcitic semi-nacre (Kouchinsky, 2000;Vendrasco et al, 2010;Vendrasco and Checa, 2015) and elongated crystal laths that are interpreted to be aragonitic (Landing and Bartowski, 1996;Kouchinsky, 2000;Landing et al, 2002;Vendrasco et al, 2010;Li et al, 2017). The chemical formation of phosphatic steinkerns is biased toward micromorphic forms (Creveling et al, 2014), suggesting some helcionelloid fossils might represent the juvenile shells (protoconchs) of macroscopic univalved mollusks (see Martí-Mus et al, 2008;Jacquet and Brock, 2016;Jacquet et al, 2016b). One of the first quantitative analyses of the fidelity of steinkern representation of the original shell identified the size of the umbilicus of anisostrophically coiled Ordovician mollusks as an indicator of the size of the original organism (Dattilo et al, 2016. This indicated the size of the steinkerns of the micromolluskan fauna studied was taphonomically, not ecologically, controlled.…”

Section: Introductionmentioning

confidence: 99%

Mollusks from the upper Shackleton Limestone (Cambrian Series 2), Central Transantarctic Mountains, East Antarctica

et al. 2019

Self Cite

View full text Add to dashboard Cite

An assemblage of Cambrian Series 2, Stages 3–4, conchiferan mollusks from the Shackleton Limestone, Transantarctic Mountains, East Antarctica, is formally described and illustrated. The fauna includes one bivalve, one macromollusk, and 10 micromollusks, including the first description of the speciesXinjispira simplexZhou and Xiao, 1984 outside North China. The new fauna shows some similarity to previously described micromollusks from lower Cambrian glacial erratics from the Antarctic Peninsula. The fauna, mainly composed of steinkerns, is relatively low diversity, but the presence of diagnostic taxa, including helcionelloidDavidonia rostrata(Zhou and Xiao, 1984), bivalvePojetaia runnegariJell, 1980, cambroclavidCambroclavus absonusConway Morris in Bengtson et al., 1990, and bradoriidSpinospitella coronataSkovsted et al., 2006, as well as the botsfordiid brachiopodSchizopholis yorkensis(Ushatinskaya and Holmer in Gravestock et al., 2001), in the overlying Holyoake Formation correlates the succession to theDailyatia odysseiZone (Cambrian Stages 3–4) in South Australia.

show abstract

“…Недавно данная биостратиграфическая схема была подвергнута резкой критике (Betts et al, 2016, p. 189): зоны определены неадекватно, на основе ограниченного массива данных и, зачастую, на основе материала плохой сохранности (внутренние ядра). В дополнение было отмечено, что кембрийские микромоллюски не могут считаться надежным биостратиграфическим инструментом, так как их распространение в существенной степени контролируется фациальными и тафономическими особенностями (Jacquet et al, 2016). Для замены "дефектной" схемы была предложена новая биостратиграфическая основа нижнего кембрия Южной Австралии (Betts et al, 2016).…”

Section: биостратиграфияunclassified

“…В последние годы изучение кембрийских моллюсков Австралии активно продолжают австралийские коллеги -Г. Брок, С. Жаке и другие специалисты (Brock, Cooper, 1993;Brock, 1998;Brock, Paterson, 2004;Topper et al, 2009;Jacquet et al, 2014Jacquet et al, , 2016Jacquet et al, , 2017Jacquet, Brock, 2016).…”

unclassified

The Cambrian molluscs of Australia: overview of taxonomy, biostratigraphy and paleobiogeography

Parkhaev

Пархаев²

2019

Стратиграфия

View full text Add to dashboard Cite

Cambrian malacofauna of Australia is among the most taxonomically diverse among time equivalents. By a number of valid mollusc species Australian Cambrian competes with Siberian and Chinese formations. Up to date, 80 valid species and 12 forms in open nomenclature, apparently representing new undescribed taxa, have been recorded from the Lower–Middle Cambrian successions of Australia. In addition, 6 species names can be considered as junior synonyms. Distribution ranges of mollusc species plotted over the modern stratigraphic scheme reveal four major molluscan evolutionary assemblages in the interval of Tommotian–Undillan stages. In paleogeographic aspect, the Cambrian malacofauna of Australia has 29 species in common with Siberian Platform, Kazakhstan, Altai-Sayan, Transbaikalia, Mongolia, South and North China, Morocco, Antarctic, Europe (Denmark, Germany), Greenland, North America, and New Zealand, providing important correlation links between these regional stratigraphic schemes.

show abstract

Lower Cambrian helcionelloid macromolluscs from South Australia

Cited by 32 publications

References 51 publications

Morphometric analysis of inter‐ and intraspecific variation in the Cambrian helcionelloid mollusc Mackinnonia

Morphometric analysis of inter‐ and intraspecific variation in the Cambrian helcionelloid mollusc Mackinnonia

Mollusks from the upper Shackleton Limestone (Cambrian Series 2), Central Transantarctic Mountains, East Antarctica

The Cambrian molluscs of Australia: overview of taxonomy, biostratigraphy and paleobiogeography

Contact Info

Product

Resources

About