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Ephippia belonging to Ceriodaphnia Dana, 1853 (Cladocera: Anomopoda: Daphniidae) from the Lower Cretaceous of Australia

Thomas A. Hegna and Alexey A. Kotov

Plain Language Abstract

Cladocerans are tiny (majority are less than 1 mm, a few are about 5–6 mm long), dominantly freshwater, free-swimming crustaceans. Many of them (in the Order Anomopoda) produce resting eggs within a protective case called an ephippium. Ephippia have a number of characteristics that allow us to tell, sometimes even at the species level (number of eggs inside, shape, ornamentation). The resistant nature of the ephippia give them a higher likelihood of making it into the fossil record. Their small size, however, often means that they are difficult to spot as fossils. Cladoceran body fossils are likewise rarely observed—despite being a ubiquitous part of freshwater ecosystems, their bodies are not mineralized or sclerotized and thus they decay away easily.

In 1986, paleontologists Jell and Duncan identified some putative cladoceran body fossils from the Lower Cretaceous Koonwarra fossil bed in Victoria, Australia. They classified these body fossils within the anomopod cladoceran family Daphnidae. However, the fossils have no identifiable synapomorpies that they share with cladocerans aside from size and shape, which they also share with juvenile clam shrimp. Thus, the body fossils must be regarded as indeterminate diplostracans.

Jell and Duncan also identified fossil cladoceran ephippia. They formally assigned the ephippia to the subfamily Daphniidae, but speculated in the text that the ephippia may belong to extant genera like Simocephalus or Ceriodaphnia. After analyzing the ephippia, we have found that some of them have the same shape and egg characteristics as modern members of Ceriodaphnia. Thus, we assign these ephippia to Ceriodaphnia sp. The presence of Ceriodaphnia-type ephippia alongside Simocephalus-type ephippia (identified by Fryer in 1991) supports the notion that the Daphniidae have deep roots in the Mesozoic, and that Ceriodaphnia was dispersed to at least two continents by the early Cretaceous.

Resumen en Español

Efipios pertenecientes a Ceriodaphnia Dana, 1853 (Cladocera: Anomopoda: Daphniidae) del Cretácico Inferior de Australia

Se informa de los primeros efipios fósiles (exuvias de cladóceros que contienen huevos en reposo) pertenecientes al género actual Ceriodaphnia (Anomopoda: Daphniidae) de la roca lacustre del Cretácico Inferior del Koonwarra Fossil Bed (Grupo Strzelecki), Sur de Gippsland, Victoria, Australia. Representan el segundo registro de efipios de cladóceros fósiles pre-cuaternarios para Australia (Ceriodaphnia y Simocephalus, ambos de Koonwarra). La presencia de ambos géneros es aproximadamente coincidente con la primera aparición de estos géneros en otras partes (i.e., Mongolia). Esto sugiere que la radiación temprana de los Daphniidae anomópodos es anterior a la desintegración de Pangea. Además, se revisan algunos fósiles corporales putativos de cladóceros de la misma localidad; aunque son consistentes con el tamaño y la forma de los cladóceros, no poseen sinapomorfias específicas de cladóceros. Por lo tanto, son considerados como diplostráceos indeterminados.

Palabras clave: Crustacea; Branchiopoda; Cladocera; Anomopoda; Daphniidae; Cretácico.

Traducción: Enrique Peñalver (Sociedad Española de Paleontología)

Résumé en Français

Des éphippies appartenant à Ceriodaphnia Dana, 1853 (Cladocera : Anomopoda : Daphniidae) du Crétacé inférieur d'Australie

Les premières éphippies (exuvies de cladocères contenant les œufs de résistance) fossiles appartenant au genre actuel Ceriodaphnia (Anomopoda : Daphniidae) sont signalées dans le Crétacé inférieur (Aptien) des dépôts de milieu d'eau douce du « Koonwarra Fossil Bed » (groupe Strzelecki, Gippsland Sud, État de Victoria, Australie). Elles représentent seulement le second signalement d'éphippies fossiles de cladocères plus anciennes que le Quaternaire en Australie (Ceriodaphnia et Simocephalus, les deux provenant de Koonwarra). L'occurrence de ces deux genres coïncide grossièrement avec la première occurrence de ces genres ailleurs (en Mongolie). Cela suggère que la radiation ancienne des anomopodes daphniidés est antérieure à la dislocation de la Pangée. De plus, certains fossiles de corps supposés appartenir à des cladocères et provenant de cette même localité sont également révisés : bien qu'ils soient cohérents en termes de taille et de forme avec les cladocères, ils ne possèdent aucune des synapomorphies des cladocères. Ils sont donc considérés comme des diplostracés indéterminés.

Mots-clés: Crustacea ; Branchiopoda ; Cladocera ; Anomopoda ; Daphniidae ; Crétacé

Translator: Antoine Souron

Deutsche Zusammenfassung

Ephippia von Ceriodaphnia Dana, 1853 (Cladocera: Anomopoda: Daphniidae) aus der unteren Kreide von Australien

Es wird über die ersten Epihippia-Fossilien (ein cladoceranes Exuvium mit Dauereiern) berichtet. Sie gehören der heutigen Gattung Ceriodaphnia (Anomopoda: Daphniidae) an und stammen aus den unterkretazischen (Aptium) Frischwassser Koonwarra Fossillagerstätten (Strzelecki Gruppe), South Gippsland, Victoria, Australien. Sie stellen erst den zweiten Nachweis (prä-quartärer) fossiler cladocerer Epihippia aus Australien dar (Ceriodaphnia und Simocephalus sind beide aus Koonwarra). Das Vorkommen beider Gattungen stimmt ungefähr mit dem ersten Auftreten dieser Gattungen andernorts (i.e. Mongolei) überein. Dies legt nahe, dass die frühe Radiation der daphniiden Anomopoden dem Auseinanderbrechen von Pangaea vorausging. Zusätzlich werden einige mutmaßliche Cladoceren -Körperfossilien aus der gleichen Fundstelle überprüft. Obwohl diese in Größe und Form mit den Cladoceren übereinstimmen zeigen sie keine für Cladoceren typische Synapomorphien und werden daher als Diplostraca indet. betrachtet.

Schlüsselwörter: Crustacea; Branchiopoda; Cladocera; Anomopoda; Daphniidae; Kreide.

Translator: Eva Gebauer

Arabic

667 arab

Translator: Ashraf M.T. Elewa

 

 

hegnaThomas A. Hegna. Department of Geology, Western Illinois University, Macomb, IL 61455, USA. This email address is being protected from spambots. You need JavaScript enabled to view it.

Thomas A. Hegna (Ph.D) is an assistant professor of paleontologist at Western Illinois University. He completed his B.S. and M.S. at the University of Iowa and his Ph.D at Yale University. He has been at WIU since 2011 and has published 19 articles in peer-reviewed journals and books. His research focuses on the taphonomy and evolution of Paleozoic and Mesozoic arthropods—in particular trilobites and branchiopod crustaceans.

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authorAlexey A. Kotov. A.N. Severtsov Institute of Ecology and Evolution, Leninsky Prospect 33, Moscow 119071, Russia and Kazan Federal University, Kremlevskaya Str.18, Kazan 420000, Russia. This email address is being protected from spambots. You need JavaScript enabled to view it.

Alexey A. Kotov (Ph. D., Dr. Sci., Professor of Russian Academy of Sciences) is a zoologist studying morphology, taxonomy, different aspects of evolution, molecular phylogenetics, ontogenesis and palaeontology of the Cladocera (Crustacea; Branchiopoda). He graduated from M.V. Lomonosov Moscow State University, Russia in 1991. Since that time, he has published two monographs, several chapters in collective monographs and 109 papers in journals represented in the Web of Science system, including a series of articles on fossil cladocerans from different Mesozoic and Cenozoic localities. A.A. Kotov has described several extinct taxa of different rank, including two orders, Cryptopoda Kotov, 2007 and Proanomopoda Kotov, 2013. Recently, he has been studying cladocerans from several Palaeogene and Neogene localities in Eurasia.

 

 

APPENDIX 1.

Additional ephippia from Koonwarra. 1-12,Ceriodaphnia sp. All scale bars = 200 µm. 1, NMV P332699. 2, NMV P332700. 3, NMV P332698. 4, NMV P332702. 5, NMV P332701. 6, NMV P109499B. 7, NMV P332693. 8, NMV P332695. 9, NMV P332692. 10, NMV P332696. 11, NMV P332694. 12, NMV P109500.

appendix

APPENDIX 2.

Table of the oldest known ephippial fossils for different cladoceran clades. Excludes Quaternary records.

Clade Age Location Citation
Daphnia (Daphnia) and D. (Ctenodaphnia) Jurassic/Cretaceous Mongolia Smirnov, 1992; Kotov and Taylor, 2011
Simocephalus Jurassic/Cretaceous Mongolia Smirnov, 1992; Kotov, 2007; Kotov and Taylor, 2011
Simocephalus (Australia) Lower Cretaceous Koonwarra Fryer, 1991
Ceriodaphnia Jurassic/Cretaceous Mongolia Smirnov, 1992; Kotov, 2009b
Ceriodaphnia (Australia) Lower Cretaceous Koonwarra Herein
Moinia Jurassic/Cretaceous NE China, Mongolia Lai, 1990; Smirnov, 1992
Bosminidae Eocene Germany Lutz, 1991
Chydoridae Lower Cretaceous Mongolia Kotov, 2009b
 

FIGURE 1. Fossil diplostracan remains from Koonwarra. 1, An image of a fossil ephippium belonging to Ceriodaphnia sp. from the Koonwarra Fossil Beds (photographed with obliquely directed light), NMV P332637, 2, Interpretive drawing of Figure 1.1, scale bar for 1-2 equals 0.1 mm. 3, Diplostracan indet, NMV P109450 (figure 70G and 71C in Jell and Duncan, 1986), See Figure 1.4 for scale bar. 4, Diplostracan indet, NMV P109462 (figure 70H and 71E in Jell and Duncan, 1986). Scale bar in 1.4 applies to 1.3 as well. Scale bar for 1.3-4 equals 1 mm. Abbreviations: aII - antenna II; hd - head; tl - thoracic limbs; vv - valves.

figure1

FIGURE 2. Modern Ceriodaphnia sp. 1, Scanning electron microscope image of a modern ephippium-bearing Ceriodaphnia sp. female (collected from Glubokoe Lake, European Russia) prior to releasing the ephippium during molting, ephippium tilted slightly away from angle of photograph, scale bar equals 0.1 mm. 2, Scanning electron microscope image of the mandibles of Daphnia magna , scale bar equals 0.1 mm.

figure2