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Sci Rep
2024 Aug 02;141:17932. doi: 10.1038/s41598-024-67687-2.
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The latest shallow-sea isocrinids from the Miocene of Paratethys and implications to the Mesozoic marine revolution.
Salamon MA
,
Radwańska U
,
Paszcza K
,
Krajewski M
,
Brachaniec T
,
Niedźwiedzki R
,
Gorzelak P
.
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The predation-driven Mesozoic marine revolution (MMR) is believed to have induced a dramatic change in the bathymetric distribution of many shallow marine invertebrates since the late Mesozoic. For instance, stalked crinoids - isocrinids (Isocrinida) have undergone a striking decline in shallow-sea environments and today they are restricted to deep-sea settings (below 100 m depth). However, the timing and synchronicity of this shift are a matter of debate. A delayed onset of MMR and/or shifts to a retrograde, low-predation community structure during the Paleogene in the Southern Ocean were invoked. In particular, recent data from the Southern Hemisphere suggest that the environmental restriction of isocrinids to the deep-sea settings may have occurred at the end of the Eocene around Antarctica and Australia, and later in the early Miocene in New Zealand. Here, we report the anomalous occurrence of the isocrinids in shallow nearshore marine facies from the middle Miocene of Poland (Northern Hemisphere, Central Paratethys). Thus, globally, this is the youngest record of shallow-sea stalked crinoids. This finding suggests that some relict stalked crinoids may have been able to live in the shallow-water environments by the middle Miocene, and further confirms that the depth restriction of isocrinids to offshore environments was not synchronous on a global scale.
Figure 1. Cenozoic occurrences of shallow-sea stalked crinoids in different continents: Europe (Refs.15–18), North America (Refs.4,19,20), South America (Refs.13,21), Australia (Refs.14,21–30), and Antarctica (Refs.10,11,14,31,32). The depth of inner shelf is understood here as approximately 40 m (for details see Fig. 2.1. in Ribeiro33).
Figure 2. Location of the investigated outcrops. On the left, location sketch of the Gołuchów and Zygmuntów on the background of middle Miocene deposits in the southern Poland (a,b). On the right, palaeogeographic location of the studied outcrops ((AF) Alpine Foredeep; (CWC) Central Western Carpathians; (NB) Novohrad-Nógrád Basin; (OWC) Outer Western Carpathians; (SB) Styrian Basin; (TCR) Transdanubian High; (VB)) (c). Redrawn and modified after Studencka et al.34; Kováč et al.35.
Figure 3. Stratigraphic scheme of the Miocene (after Steininger et al.48) and stratigraphic schemes for the foredeep depozone of the Fore-Carpathian Basin in Poland (modified after Jasionowski49; Oszczypko et al.37).
Figure 4. Polished slabs from Gołuchów Quarry. (a) Bioclastic floatstone/rudstone with numerous large Badenian benthic foraminifers (arrows), bivalve shells, bored algae (A) and oolitic clasts (Jkm). (b) bioclastic-bivalve floatstone with thick-shelled parallel or chaotic distributed bivalves and bryozoans (arrows). In calcareous matrix visible numerous small quartz grains.
Figure 5. Microfacies from study oucrops. (a) bioclastic sandstone; visible mainly quartz grains, calcareous matrix and fragments of bivalves and polychaetes. (b) bivalve-bioclastic floatstone. (c) foraminifer-algae floatstone/rudstone with numerous large benthic foraminifers (arrows) and bored algaes (A); in the lower part clast of ooid limestone (Jkm). (d) bioclastic-reach sandstone with large benthic foraminifers (arrows), bryozoans (B), bivalves. (e, f) calcareous sandstone with numerous benthic foraminifers (arrows), bryozoans (B), shells of bivalves and polychaetes.
Figure 6. Metacrininae gen. et sp. indet. from Miocene (Badenian) strata of southern Poland. Scale bar equals 1 mm. (a) articular facet of proximal columnal (a1) and oblique view of proximal pluricolumnal (a2). Zygmuntów locality. GIUS 12–1475/8. (b) Articular facet of proximal columnal (b1) and enlargement of petal floor (b2). Zygmuntów locality. GIUS 12-1475/9. (c) oblique view of cirral. Gołuchów locality. GIUS 12-1475/3. (d) Proximal facet of secundibrachial. Gołuchów locality. GIUS 12-1475/4. (e) oblique view of distal columnal. Gołuchów locality. GIUS 12-1475/1. (f) articular facet of distal/medial columnal (f1) and oblique view of distal/medial pluricolumnal (f2). Gołuchów locality. GIUS 12-1475/5. (g) oblique view of distal/medial pluricolumnal. Gołuchów locality. GIUS 12-1475/7.