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A problematic soft-bodied fossil from the Cambrian (Miaolingian, Wuliuan) of Utah

Published online by Cambridge University Press:  18 September 2025

Julien Kimmig Open the ORCID record for Julien Kimmig [Opens in a new window] ,
Karma Nanglu  and
Paul G. Jamison
Julien Kimmig*
Affiliation:
The Harold Hamm School of Geology and Geological Engineering, University of North Dakota, Grand Forks, ND, USA Paläontologie und Evolutionsforschung, Abteilung Geowissenschaften, Staatliches Museum für Naturkunde Karlsruhe, Karlsruhe, Germany Institute of Applied Geosciences (AGW), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
Karma Nanglu
Affiliation:
Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada Department of Earth and Planetary Sciences, University of California Riverside, Riverside, CA, USA
Paul G. Jamison
Affiliation:
Department of Geosciences, Utah State University, Logan, UT, USA
*
Corresponding author: Julien Kimmig; Emails: julien.kimmig@und.edu julien.kimmig@smnk.de
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Abstract

The Spence Shale of Utah and Idaho preserves a diverse soft-bodied biota from the Cambrian. While the fauna is dominated by arthropods and echinoderms, soft-bodied animals belonging to other groups are known. Here we document Tentalus spencensis gen. et sp. nov. from the High Creek locality of the Spence Shale. The fossil has a crown of short stubby tentacles and appears to have been attached to the sediment through a stalk. The morphology of Tentalus suggests that it is a dinomischiid or deuterostome; however, it cannot be attributed to any of the known species, based on the short and conical tentacles surrounding an oral region, and polyp-like oblong columnar trunk terminating in a stalk, that do not resemble any described species.

Keywords

Great BasinLagerstätteLaurentiaSpence Shalefilter feedingDeuterostomiaDinomischus

Information

Type
Rapid Communication
Information
Geological Magazine , Volume 162 , 2025 , e37
Creative Commons
Creative Common License - CCCreative Common License - BY
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.
Copyright
© The Author(s), 2025. Published by Cambridge University Press

1. Introduction

The Cambrian exposures of the Great Basin yield several Fossil-Lagerstätten (sensu Kimmig & Schiffbauer, Reference Kimmig and Schiffbauer2024) that have provided important information into the understanding of the early evolution of life. Among them, the Spence Shale Lagerstätte (Spence Shale hereafter) of northeastern Utah and southeastern Idaho preserves one of the most diverse biotas of Laurentia (Briggs & Robison, Reference Briggs and Robison1984; Briggs et al. Reference Briggs, Lieberman, Hendricks, Halgedahl and Jarrard2008; Kimmig et al. Reference Kimmig, Strotz, Kimmig, Egenhoff and Lieberman2019a , Reference Kimmig, Pates, LaVine, Krumenacker, Whitaker, Strotz, Jamison, Gunther, Gunther, Witte, Daley and Lieberman2023, Reference Kimmig, LaVine, Schiffbauer, EWgenhoff, Shelton and Leibach2024; Whitaker & Kimmig, Reference Whitaker and Kimmig2020). Its fauna comprises over 100 species, of which about one-third are soft-bodied (Robison et al. Reference Robison, Babcock and Gunther2015; Kimmig et al. Reference Kimmig, Strotz, Kimmig, Egenhoff and Lieberman2019a , Reference Kimmig, Pates, LaVine, Krumenacker, Whitaker, Strotz, Jamison, Gunther, Gunther, Witte, Daley and Lieberman2023, Reference Kimmig, LaVine, Schiffbauer, EWgenhoff, Shelton and Leibach2024; Whitaker & Kimmig, Reference Whitaker and Kimmig2020; Whitaker et al. Reference Whitaker, Jamison, Schiffbauer and Kimmig2020, Reference Whitaker, Schiffbauer, Briggs, Leibach and Kimmig2022). While the fauna is dominated by panarthropods and echinoderms, soft-bodied animals belonging to other groups are diverse, but rarely abundant (Robison et al. Reference Robison, Babcock and Gunther2015; Kimmig et al. Reference Kimmig, Strotz, Kimmig, Egenhoff and Lieberman2019a , Reference Kimmig, Pates, LaVine, Krumenacker, Whitaker, Strotz, Jamison, Gunther, Gunther, Witte, Daley and Lieberman2023, Reference Kimmig, LaVine, Schiffbauer, EWgenhoff, Shelton and Leibach2024; Whitaker & Kimmig, Reference Whitaker and Kimmig2020; Foster et al. Reference Foster, Sroka, Howells, Cothren, Dehler and Hagadorn2022; Yang et al. Reference Yang, Kimmig, Pates, Jamison and Ma2025). Most of the soft-bodied taxa are limited to the Lagerstätten intervals in the Wellsville Mountains (Kimmig et al. Reference Kimmig, Strotz, Kimmig, Egenhoff and Lieberman2019a ; Whitaker & Kimmig, Reference Whitaker and Kimmig2020), but other outcrops of the Spence Shale have yielded some soft-bodied taxa, with the High Creek locality north of Logan, Utah preserving the most abundant outside of the Wellsville Mountains (Kimmig et al. Reference Kimmig, Strotz, Kimmig, Egenhoff and Lieberman2019a , Reference Kimmig, Pates, LaVine, Krumenacker, Whitaker, Strotz, Jamison, Gunther, Gunther, Witte, Daley and Lieberman2023; Whitaker et al. Reference Whitaker, Schiffbauer, Briggs, Leibach and Kimmig2022).

Here, we document and describe Tentalus spencensis gen. et sp. nov., a new putative dinomischiid or deuterostome known from a single specimen from the High Creek location of the Spence Shale (Cambrian, Miaolingian, Wuliuan) of Utah, USA. As this fossil is unlike any known Cambrian tentacle-bearing fossil (e.g., Caron et al. Reference Caron, Conway Morris and Shu2010; Conway Morris, Reference Conway Morris1977; Jin et al. Reference Jin, Yuanlong and Jih-Pai2006; Nanglu et al. Reference Nanglu, Cole, Wright and Souto2023) or fossil from the Spence Shale, we discuss its potential affinities.

2. Geological setting

The Spence Shale Member of the Langston Formation is regionally extensive with outcrops in southeastern Idaho and northeastern Utah (Fig. 1). The Spence Shale Member ranges in age from Mexicella mexicana to Glossopleura walcotti biozones (Cambrian, Miaolingian, Wuliuan, 507.5–506 Myr) (Liddell et al. Reference Liddell, Wright and Brett1997; Kimmig et al. Reference Kimmig, Strotz, Kimmig, Egenhoff and Lieberman2019a ), with all soft-bodied fossils to date coming from the Glossopleura walcotti Biozone. It was deposited on a slope on the passive western margin of Laurentia, as suggested by the wackestones, marls and siliciclastic mud-rich carbonate mudstones and contain some laminae of intercalated packstones (Kimmig et al. Reference Kimmig, LaVine, Schiffbauer, EWgenhoff, Shelton and Leibach2024) and outcrops record an overall increase in depth from Utah to Idaho. The Spence Shale Member ranges from ∼9 m at Blacksmith Fork to ∼120 m at Oneida Narrows (Walcott Reference Walcott1908; Deiss Reference Deiss1938; Liddell et al. Reference Liddell, Wright and Brett1997) and conformably overlies the Naomi Peak Limestone Member of the Langston Formation. The High Creek Limestone member of the Langston Formation in turn conformably overlies the Spence Shale Member.

Figure 1. Locations of the Spence Shale Lagerstätte: (a) map of the western USA showing the location of the Spence Shale; (b) geological map (based on the USGS state maps for Google Earth Pro) of northern Utah and southern Idaho showing the principal localities within the Spence Shale; (c) simplified stratigraphy of the Langston Formation at High Creek. AC, Antimony Canyon; BF, Blacksmith Fork; HC, Hansen Canyon; HCL, High Creek Limestone Member; HCR, High Creek; MH, Miners Hollow; NPL, Naomi Peak Limestone Member.

The specimen was found in the middle of the Spence Shale Member at the High Creek locality in the Bear River Range, north of Logan Utah. Due to local faulting in the area, part of a larger fault system in northeastern Utah (Williams Reference Williams1948; Valenti Reference Valenti and Powers1982; McCalpin Reference McCalpin and Lund1994; Evans & Oaks, Reference Evans and Oaks1996; Black et al. Reference Black, Giraud, Mayes and Lund2000; Whitaker et al. Reference Whitaker, Schiffbauer, Briggs, Leibach and Kimmig2022), it is unclear exactly at what height compared to the reference section (Fig. 1c). In the High Creek area, the Spence Shale exposes carbonate facies belts as well as transitional siliciclastic-carbonate facies (siliciclastic mud-rich, carbonate mudstones) of a Cambrian carbonate ramp system (Kimmig et al. Reference Kimmig, LaVine, Schiffbauer, EWgenhoff, Shelton and Leibach2024). The facies change up-section. The succession is interpreted as having been deposited in a ramp-like setting with minor relief, based on the absence of synsedimentary deformation features such as slumps. The succession, as a whole, reflects a decrease in water depth, as the progressive decrease in carbonate mud throughout the succession reflects an increase in depositional energy up-section. Based on the preserved fossil remains, there seems to be an increase in fossil abundance up-section, too, indicating an increase in biodiversity towards shallower water environments (Kimmig et al. Reference Kimmig, LaVine, Schiffbauer, EWgenhoff, Shelton and Leibach2024). SMNK-PAL 73174 was recovered from an interval of siliciclastic mud-rich carbonate mudstones.

3. Material and methods

The specimen was collected by Paul Jamison and is reposited at the Staatliches Museum für Naturkunde Karlsruhe, Karlsruhe, Germany, with a permit from the U.S. Department of Agriculture Forest Service to JK. The specimen was collected with hand tools.

The specimen was photographed with a Canon EOS R5 camera mounted with an EF 100 f/2.8 Macro IS USM lens. The specimen was photographed under white light and cross polarized light in two mediums – air and immersed in ethanol. Close-ups were captured using a Keyence VHX 7000 digital microscope under white light.

The colour, contrast and brightness of the images were adjusted using Adobe Photoshop. Line drawings were made with Adobe Illustrator. Specimen measurements were made from photographs in ImageJ (Schneider et al. Reference Schneider, Rasband and Eliceiri2012).

Institutional Abbreviations: KUMIP, Division of Invertebrate Paleontology, Biodiversity Institute, University of Kansas, Lawrence, USA; ROM and ROMIP, Royal Ontario Museum, Toronto, Ontario, Canada; SMNK, Staatliches Museum für Naturkunde Karlsruhe, Karlsruhe, Germany; USNM, National Museum of Natural History [United States National Museum], Washington, DC, USA.

4. Systematic paleontology

Phylum Uncertain

Tentalus gen. nov.

LSID. urn:lsid:zoobank.org: 71D37695-B25A-4CCA-95F4-669DF6903484

Etymology. Tentalus after the fictional boss in the game The Legend of Zelda: Skyward Sword, in reference to its crown of tentacles.

Type species. Tentalus spencensis sp. nov.

Localities and horizon. As for the type species, by monotypy.

Diagnosis. As for the type species, by monotypy.

Tentalus spencensis sp. nov.

Figure 2

Figure 2. Tentalus spencensis gen. et sp. nov. from the Spence Shale Member, Langston Formation (Cambrian: Wuliuan), Utah, USA. (a) SMNK-PAL 73174 laterally preserved. (b) Interpretative drawing of SMNK-PAL 73174. (c) Close-up of the preserved calyx. (d) Close-up of the partial stalk. (e) Close-up of the right tentacles preserving faint striations. (f) Close-up of the anterior part. Scale bars are 1 mm. c = calyx; pin? = putative pinnules; st = stalk; te = tentacle.

LSID. urn:lsid:zoobank.org: 14A8730C-B7E7-4514-929C-8BE146AF8A26

Etymology. spencensis after the type deposit.

Holotype. SMNK-PAL 73174, part of laterally preserved specimen.

Locality and horizon. SMNK-PAL 73174 originates from the middle of the Wuliuan Spence Shale Member (Glossopleura walcotti Biozone) of the Langston Formation, High Creek locality, ∼25 km north of Logan, Wasatch Range, Cache County, Utah, USA, Sec. 3 T13N, R02E (GPS: 41.896, –111.711).

Diagnosis. Solitary, with a whorl of at least 14 tentacles surrounding an oral region, polyp-like oblong columnar trunk terminating in a stalk. Tentacles are short and conical.

Description. The body of the holotype and only known specimen is 10.4 mm long and 7.2 mm wide. The body is oblong, preserves tentacles at the anterior end and tapers slightly at the posterior end.

The anterior end preserves at least 14 tentacles. The tentacles are conical in shape, and on average, 2.7 mm long and about 0.9 mm at the base. Some tentacles preserve striations (Fig. 2d), which might represent pinnules. As the tentacles are all straight and elongated, it is possible that they were relatively stiff, as has been suggested for Dinomischus (Zhao et al. Reference Zhao, Vinther, Parry, Hou, Edgecombe, Cong, Zhao, Vinther, Parry, Wei, Green, Pisani and Hou2019).

The posterior end of the calyx tapers and extends into a stalk that is about 2.4 mm wide. The stalk is poorly preserved, and it is unclear how long it is, or if a terminal disc or holdfast were present.

Remarks. In over 60 years of fossil collecting at the High Creek locality, this is the only specimen of T. spencensis that has been found. It is unclear whether or not T. spencensis had a long stalk and holdfast, as the lowermost part of the specimen is not preserved. It differs from Siphusauctum lloydguntheri Kimmig et al. Reference Kimmig, Strotz and Lieberman2017 by preserving a crown of short tentacles, a less tapering calyx, and the stalk of T. spencensis does not appear to have a division into an inner and outer layer. T. spencensis differs from Dinomischus isolatus Conway Morris, Reference Conway Morris1977 from the Burgess Shale and Kaili biota, by preserving shorter tentacles and having less of a tapering calyx. T. spencensis differs from Dinomischus venustus Chen, Hou & Hao-Zhi, Reference Chen, Hou and Hao-Zhi1989 from the Chengjiang biota, by preserving shorter tentacles, the lack of a long central tubular structure and less of a tapering calyx.

5. Discussion

5.a. Affinities of Tentalus spencensis

The appearance, but partial preservation, of T. spencensis gen et sp. nov., leaves some possibilities regarding its affinities. Here we compare T. spencensis to several taxa it might be related to.

5.a.1. Stalked enigmatica - Cotyledion, Dinomischus, and Siphusauctum

T. spencensis has several similarities with the Cambrian genera Dinomischus (Fig. 3a) and Cotyledion. The former is known from both the middle Cambrian of North America and China (Conway Morris, Reference Conway Morris1977; Jin et al. Reference Jin, Yuanlong and Jih-Pai2006), while the latter is known exclusively from China (Zhang et al. Reference Zhang, Holmer, Skovsted, Brock, Budd, Fu, Zhang, Shu, Han, Liu and Wang2013). These taxa have an elongate calyx that terminates in a crown of tentacle-like appendages. These appendages are thought to be able to move independently and are broad and flattened in morphology, similar to the tentacles of T. spencensis. Their position and arrangement are also similar to T. spencensis, appearing in lateral view as a single row of flattened petal-like structures connecting directly to and pointing away from the visceral mass. T. spencensis also has a similarly shaped visceral cavity, although its incompleteness precludes a full description of shape.

Figure 3. Potentially related taxa. (a) Dinomischus isolatus holotype from the Burgess Shale, USNM 198735. (b) Siphusauctum lloydguntheri holotype from the Spence Shale, KUMIP 135150. (c) Herpetogaster collinsi from the Pioche Formation, KUMIP 482878. (d) Close-up of the stem-calyx area of Dinomischus isolatus from the Burgess Shale, ROM 32573. (e) Close-up of the stem-calyx area of Siphusauctum gregarium from the Burgess Shale, ROM 61415. (f) Close-up of the stem-calyx area of (g) close-up of the tentacles of Dinomischus isolatus from the Burgess Shale, USNM 198735. (h) Close-up of the comb segments of Siphusauctum gregarium from the Burgess Shale, ROM 61415. (i) Close-up of the tentacles of Herpetogaster collinsi from the Burgess Shale, ROM 58051. Scale bars are 5 mm (a–c, g–i), and 1 mm (d–f).

T. spencensis has also some similarities with the stalked filter feeder Siphusauctum (Fig. 3b), which is known from the Burgess Shale and the Spence Shale (O’Brien & Caron Reference O’Brien and Caron2012; Kimmig et al. Reference Kimmig, Strotz and Lieberman2017). Siphusauctum has a wine-glass-shaped calyx, which terminates in a crown of elongated feather-like appendages that move food towards the central opening.

Both Dinomischus and Siphusauctum have been considered stem-ctenophores (Zhao et al. Reference Zhao, Vinther, Parry, Hou, Edgecombe, Cong, Zhao, Vinther, Parry, Wei, Green, Pisani and Hou2019), and Dinomischus has most recently been considered a cnidarian (Ou et al. Reference Ou, Shu, Zhang, Han, Van Iten, Cheng, Sun, Yao, Wang and Mayer2022). If these assignments are correct, and these taxa can be considered close relatives of T. spencensis, a deuterostome affinity would likely not be the case.

5.a.2. Cnidarian

T. spencensis has some similarities with sessile cnidarians, such as sea anemones (Actiniaria). It appears to have a columnar trunk topped by an oral disc with a ring of tentacles and a central mouth, and the anthozoan body plan is well documented from Cambrian localities in China (Ou et al. Reference Ou, Shu, Zhang, Han, Van Iten, Cheng, Sun, Yao, Wang and Mayer2022; Zhao et al. Reference Zhao, Parry, Vinther, Dunn, Li, Wei, Hou and Cong2023; Lei et al. Reference Lei, Han, Ou and Wan2014). However, there is no indication that the tentacles can be retracted, nor are they as long and prehensile as those seen in Cambrian cnidarians such as Nailiana (Ou et al. Reference Ou, Shu, Zhang, Han, Van Iten, Cheng, Sun, Yao, Wang and Mayer2022). The trunk shows no indication of tubercles, and while it also unclear if the stalk of T. spencensis ends in a pedal disk or a holdfast, we see no evidence of mesentery divisions (Hou et al. Reference Hou, Stanley, Zhao and Ma2005) or fine longitudinal striations (Ou et al. Reference Ou, Shu, Zhang, Han, Van Iten, Cheng, Sun, Yao, Wang and Mayer2022).

5.a.3. Ambulacrarian

A wide variety of ambulacrarian taxa are tentaculate, sessile and have holdfasts or other benthic attachment structures, which are similar to the morphology of T. spencensis. However, several key features, and the absence of others, make a placement within Ambulacraria problematic. First, T. spencensis preserves no immediate evidence of either ossicles or stereom and is thus unlikely to represent any kind of echinoderm. This includes the possible stem-group echinoderm or stem-group ambulacrarian Yanjiahella biscarpa (Topper et al. Reference Topper, Guo, Clausen, Skovsted and Zhang2019; Zamora et al. Reference Zamora, Wright, Mooi, Lefebvre, Guensburg, Gorzelak, David, Sumrall, Cole, Hunter and Sprinkle2020), which is further differentiated from T. spencensis by having only a single pair of elongate tentacles, rather than circum-oral, broad appendages.

Another ambulacrarian group with some comparable features are the cambroernids. This includes a variety of discoidal animals such as Eldonia, Stellostomites and Rotadiscus, as well as Herpetogaster collinsi (Fig. 3c). The latter is known from the Burgess Shale and also the slightly older Pioche and Balang formations (Caron et al. Reference Caron, Conway Morris and Shu2010; Kimmig et al. Reference Kimmig, Meyer and Lieberman2019b ; Yang et al. Reference Yang, Kimmig, Schiffbauer and Peng2023). In contrast to T. spencensis, Herpetogaster collinsi, however, has a segmented body and only two branching tentacles with dendritic extensions, rather than flattened with striations.

5.b. Other soft-bodied deuterostomes of the Spence Shale

As Tentalus T. spencensis might be a deuterostome based on the presence of tentacles, sessile lifestyle, and benthic attachment structures, as discussed above, it is worth considering the other known deuterostomes from the Spence Shale.

The first undoubted deuterostomes appear in the fossil record of Cambrian Stage 3 (Nanglu et al. Reference Nanglu, Cole, Wright and Souto2023; Rahman & Zamora, Reference Rahman and Zamora2024), and the first soft-bodied deuterostomes from Laurentia, Herpetogaster, are known from Cambrian Stage 4 (Kimmig et al. Reference Kimmig, Meyer and Lieberman2019b ). By the Wuliuan Stage, the three main deuterostome Phyla (Hemichordata, Echinodermata and Chordata) are known from Laurentia (Kimmig et al. Reference Kimmig, Strotz, Kimmig, Egenhoff and Lieberman2019a ; Nanglu et al. Reference Nanglu, Caron and Gaines2020; Rahman & Zamora, Reference Rahman and Zamora2024), and all of them have been found in the Spence Shale (Kimmig et al. Reference Kimmig, Strotz, Kimmig, Egenhoff and Lieberman2019a ; Rahman & Zamora, Reference Rahman and Zamora2024). In terms of soft-bodied deuterostomes, four taxa are known, Banffia episoma, Eldonia ludwigi, Sphenoecium wheelerensis and Yuknessia.

Banffia episoma is the only vetulicolian known from the Spence Shale (Conway Morris et al. Reference Conway Morris, Halgedahl, Selden and Jarrard2015a ; Ma et al. Reference Ma, Kimmig, Schiffbauer, Li, Peng and Yang2025). It is relatively abundant with about a dozen specimens in museum collections, but is restricted to the shales of the Wellsville Mountain section, suggesting that it preferred deeper water environments. The most recent phylogenetic analysis (Mussini et al., Reference Mussini, Smith, Vinther, Rahman, Murdock, Harper and Dunn2024) suggests that vetulicolians are a paraphyletic group amongst stem-chordates, making Banffia episoma the first record of chordates in Laurentia.

Similar to Banffia episoma, the phylogenetically problematic Eldonia ludwigi (Conway Morris et al. Reference Conway Morris, Selden, Gunther, Jamison and Robison2015b ; Whitaker et al. Reference Whitaker, Schiffbauer, Briggs, Leibach and Kimmig2022), currently considered a stem-ambulacrarian (Nanglu et al. Reference Nanglu, Cole, Wright and Souto2023), is only found in the Wellsville Mountains, but can be highly abundant in areas, i.e., KUMIP 490969-491039 are part of large clusters of small Eldonia ludwigi and the KUMIP collection houses 144 specimens from the Spence Shale alone.

In terms of hemichordates, the graptolites Sphenoecium wheelerensis and Yuknessia have been described from the Spence Shale (LoDuca et al. Reference LoDuca, Wu, Zhao, Xiao, Schiffbauer, Caron and Babcock2015; Maletz & Steiner, Reference Maletz and Steiner2015). However, while the colonial organization is verified for Sphenoecium (Maletz, Reference Maletz2024), the graptolite material assigned to Yuknessia requires further study. Graptolites have been found in the Wellsville Mountains and High Creek (Kimmig et al. Reference Kimmig, Strotz, Kimmig, Egenhoff and Lieberman2019a ; Whitaker et al. Reference Whitaker, Schiffbauer, Briggs, Leibach and Kimmig2022) and are the most ecologically and geographically distributed of the soft-bodied deuterostomes in the Spence Shale.

Interestingly, no soft-bodied deuterostomes have been found in the Spence Gulch, or Blacksmith Fork locations. However, soft tissues have been found there and Spence Gulch also preserves echinoderms (Kimmig et al. Reference Kimmig, Strotz, Kimmig, Egenhoff and Lieberman2019a , Reference Kimmig, Pates, LaVine, Krumenacker, Whitaker, Strotz, Jamison, Gunther, Gunther, Witte, Daley and Lieberman2023; Wen et al. Reference Wen, Babcock, Peng and Robison2019), suggesting that the conditions might have been suitable. Different taphonomic conditions (Whitaker et al. Reference Whitaker, Schiffbauer, Briggs, Leibach and Kimmig2022) are most likely the reason for this, but anthropogenic collections biases (Whitaker & Kimmig, Reference Whitaker and Kimmig2020) have also led to a smaller sample size from these localities.

6. Conclusions

Although T. spencensis gen. et. sp. nov. is very rare, its characterizing features are well preserved, such that it is possible to distinguish it from other known tentacle-bearing organisms of the Cambrian. The differences lie outside the degree of biological or taphonomical variation that would be expected from organisms such as Dinomischus, Siphusauctum or Herpetogaster and as such warrants the establishment of a new genus and species. In particular, the short stubby tentacles and oblong calyx shape suggest this. The occurrence of T. spencensis extends the diversity of the enigmatic group of early Paleozoic stalked filter feeders. The tentacles and calyx shape suggest a relationship with other Cambrian taxa, such as Dinomischus or possibly, but less likely early deuterostomes.

Acknowledgements

We thank Bruce Schumacher (USDA Forest Service) for permits, Jean-Bernard Caron (ROMIP) for the images of Dinomischus isolatus, Herpetogaster collinsi and Siphusauctum gregarium and we thank Mathias Vielsäcker (SMNK) for specimen images. We would like to thank Jean Vannier, Russell Bicknell, an anonymous reviewer, and the Associate Editor Bas Van de Schootbrugge for their time and comments that have improved the manuscript.

Competing interests

The authors declare no competing interests.

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Figure 0

Figure 1. Locations of the Spence Shale Lagerstätte: (a) map of the western USA showing the location of the Spence Shale; (b) geological map (based on the USGS state maps for Google Earth Pro) of northern Utah and southern Idaho showing the principal localities within the Spence Shale; (c) simplified stratigraphy of the Langston Formation at High Creek. AC, Antimony Canyon; BF, Blacksmith Fork; HC, Hansen Canyon; HCL, High Creek Limestone Member; HCR, High Creek; MH, Miners Hollow; NPL, Naomi Peak Limestone Member.

Figure 1

Figure 2. Tentalus spencensis gen. et sp. nov. from the Spence Shale Member, Langston Formation (Cambrian: Wuliuan), Utah, USA. (a) SMNK-PAL 73174 laterally preserved. (b) Interpretative drawing of SMNK-PAL 73174. (c) Close-up of the preserved calyx. (d) Close-up of the partial stalk. (e) Close-up of the right tentacles preserving faint striations. (f) Close-up of the anterior part. Scale bars are 1 mm. c = calyx; pin? = putative pinnules; st = stalk; te = tentacle.

Figure 2

Figure 3. Potentially related taxa. (a) Dinomischus isolatus holotype from the Burgess Shale, USNM 198735. (b) Siphusauctum lloydguntheri holotype from the Spence Shale, KUMIP 135150. (c) Herpetogaster collinsi from the Pioche Formation, KUMIP 482878. (d) Close-up of the stem-calyx area of Dinomischus isolatus from the Burgess Shale, ROM 32573. (e) Close-up of the stem-calyx area of Siphusauctum gregarium from the Burgess Shale, ROM 61415. (f) Close-up of the stem-calyx area of (g) close-up of the tentacles of Dinomischus isolatus from the Burgess Shale, USNM 198735. (h) Close-up of the comb segments of Siphusauctum gregarium from the Burgess Shale, ROM 61415. (i) Close-up of the tentacles of Herpetogaster collinsi from the Burgess Shale, ROM 58051. Scale bars are 5 mm (a–c, g–i), and 1 mm (d–f).