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Home , Aysheaia, Onychophora, Xenusion

JOURNAL OF PALEONTOLOGY,V. 54, NO. 3, P. 588-596, 3 PLS., 2 TEXT-FIGS., MAY 1980

A POSSIBLE ONYCHOPHORAN FROM THE MIDDLE MAZON CREEK BEDS OF NORTHERN ILLINOIS

IDA THOMPSON AND DOUGLAS S. JONES Department of Geological and Geophysical Sciences, Princeton University, Princeton, New Jersey 08544

ABSTRACT-Alobopod , Helenodora inopinata n.gen., n.sp., is described from two specimens preserved in siderite concretions from the Middle Pennsylvanian Francis Creek Shale, Illinois. The specimens are characterized by a long, vermiform trunk bearing 21 or more pairs of short, lobose limbs ventro-laterally placed. One limb is preserved with two small hook-like claws. Other limbs have suggestions of claws. The body is annulated, with about nine annulations per limb-bearing section. The annulations bear small papillae. The head and posterior end are poorly preserved but there is a suggestion of jaws indicating a ventral mouth in both specimens. All preserved character- istics are compatible with assignment of H. inopinata to the subphylum . However, because of the poor preservation of the anterior and posterior, assignment is made only to the Manton, 1972. Since the Mazon Creek beds contain a mixture of terrestrial, freshwater, and marine organisms, the of this species remains uncertain.

INTRODUCTION from the Mazon Creek beds of Northern Illi- THE FOSSILRECORD of onychophorans is very nois. This extraordinary locality has already poor or non-existent (Dechaseaux, 1953). The yielded many organisms rare or unique in the classification of two species assigned in fossil record. The most famous example is the the past to the Onychophora is now uncertain. legendary Tullimonstrum gregarium (Richard- The most famous "onychophoran," son and Johnson, 1966), a strange, soft-bodied pedunculata from the Middle Bur- with segmented trunk, clawed gess Shale (Walcott, 1911, 1931; Hutchinson, proboscis, and eyes on a bar organ. Other un- 1930, 1969; Delle Cave and Simonetta, 1975), usual finds include a large hydra (Schram and has recently been thoroughly restudied by Nitecki, 1975); the earliest fossil squid, com- Whittington (1978) who concludes that the dif- plete with tentacles (Johnson and Richardson, ferences between Aysheaia and living ony- 1966); the only fossil echiuran (Jones and chophorans are extreme. Whittington (1978) Thompson, 1977); a diverse collection of prefers not to assign Aysheaia to any higher whole-bodied (Thompson, 1979); while allowing for the possibility that and other (Schram, 1973). the group to which Aysheaia belonged could have been ancestral to the living uniramians SYSTEMATIC PALEONTOLOGY (including onychophorans). The other possible onychophoran is Xenu- Phylum UNIRAMIA Manton, 1972 sion auerswaldae (Pompeckj, 1927), recovered Subphylum ONYCHOPHORA? Grube, 1853 from an erratic block found in northern Ger- HELENODORA n.gen. many. This block may be from lowermost Diagnosis.-Same as for the only species. Cambrian quartzites in southeastern Sweden Type species.-Helenodora inopinata, n.sp. (Jaeger and Martinsson, 1967). Tarlo (1967) classifies as a coelenterate of the HELENODORA INOPINATA, n.sp. Rangea-Charnia type. Whitting- Text-fig. 1; PI. 1; PI. 2; PI. 3, figs. 1, 2, 4 ton considers this "plausible" (Whittington, Types.-Holotype: FMNH PE 29049 (Text- 1978). However Xenusion continues to be dis- fig. 1A; PI. 1; PI. 3, figs. 1, 2, 4). Paratype: cussed as a possible onychophoran (Berg- FMNH PE 29050 (Text-fig. 1B; PI. 2; PI. 3, strom, 1979, p. 11). fig. 4). Both types are part and counterpart of The organism described here as another small siderite concretions in the invertebrate possible onychophoran is known from two fossil collection of the Field Museum of Nat- specimens preserved in siderite concretions ural History, Chicago, Illinois.

Copyright ( 1980, The Society of Economic Paleontologists and Mineralogists 588 0022-3360/80/0054-0588$03.00 MAZON CREEK ONYCHOPHORAN 589

Reconstruction.-Text-fig. 2B. Diagnosis.-Elongated, vermiform with 21 or more pairs of short, tapered legs A, W - aX Z2 A WJAW ? and 3 1 arranged ventro-laterally evenly spaced 6 5 4 along body; with fine annulations, ap- 10mm proximately nine per segment with the ridges B 14 13 12 11 10 9 of each annulation bearing tiny papillae spaced about three per mm. Stratigraphic position and locality.-Mid- dle Pennsylvanian, Desmoinesean (Westpha- lian D). Carbondale Formation, Francis Creek 'CLAW JAW Shale. Both specimens are from strip mine Pit TEXT-FIG.1-Camera lucida line drawings of He- lenodora Eleven, Coal Will and inopinatan.gen., n.sp. Appendagesare Peabody Company, numbered from the anterior in both Kankakee U.S.A. (right spec- counties, Illinois, imens). Shaded areas represent annulated patches Etymology.-The generic name, Heleno- of cuticle. A, holotype-FMNH PE 29049. B, dora, is Greek for Helen's gift and honors Mrs. paratype-FMNH PE 29050. Helen Piecko of Chicago, Illinois, who found the only two known specimens of this species and donated them to the Field Museum. In- presence of the trunk over it. The paratype, opinata is Latin for unexpected. however, must have the ventral surface ex- Material.-Only two specimens of Heleno- posed because of the fidelity with which the dora inopinata are known. Both are contained left row of legs is preserved within the body in concretions which have split in the plane of profile. Rotation was to the right and the right the fossils. The fossils are light brown in color row of legs is outlined (Text-fig. 1B). and thus stand out against the surrounding Description.-Dimensions.-The trunk of dark brown rock matrix, a common mode of the holotype measures 56 mm in length and 6 preservation in Mazon Creek material. mm in width. The slightly larger paratype is The fossils show some relief with the legs 64 mm long and 13 mm wide. slightly raised or depressed relative to the Legs.-There are two rows of paired, ven- plane of the body (PI. 1, fig. 2; PI. 2, fig. 2). tro-lateral legs. Each leg is preserved as a The texture of the cuticle is accentuated with stubby triangle, tapering distally. The number oblique lighting (PI. 2, fig. 3). Much of this of pairs of legs is uncertain and may be dif- study was done with the specimens under ferent in the two specimens. The holotype water to accentuate color differences and min- (Text-fig. 1A) has 22 or 23 pairs of imize surface irregularities. that are most clearly defined on the right (low- We are not certain of the orientation of the er) margin. The presumed anterior is incom- fossils. In each specimen, one end tapers plete because the concretion failed to split in slightly more than the other end (Text-fig. 1). the exact plane of the head; but because of the The more tapered end in each case contains a pronounced taper, we suspect very little of the small dark patch in the approximate position head is missing. 1 (Text-fig. 1A) of the jaw in living onychophorans. In addi- may be an incomplete leg or the base of an tion, in the paratype this tapered end termi- . Posteriorly there may be one or more nates in two paired appendages that look more legs missing. The minimum number of leg like stubby antennae or the bases of antennae pairs for the holotype is 21. The left row of than they do legs. For these reasons, we will legs is much more obscurely preserved within refer to the tapered ends as anterior and des- the body margin (Text-fig. 1A) as slight ignate right and left on this basis, but these depressions which show dark outlines when designations are not conclusive. the fossil is wet. Some of the cuticle with trans- Both specimens are dorso-ventrally flat- verse annulations lies over the legs, obscuring tened with some longitudinal rotation. The them. holotype shows the dorsal surface and right- The paratype (Text-fig. 1B) shows 21 pairs lateral side with the right legs outlined; there- of appendages. If the anterior-most of these fore, rotation was to the left (Text-fig. 1A). are antennae and the second pair are oral pa- The obscurity of the left leg row is due to the pillae, then this specimen has a minimum of 590 IDA THOMPSON AND DOUGLAS S. JONES

19 pairs of legs. Most of the right (upper) leg some lobe-like relief. The patch in the para- row projects from the body margin, as in the type is smaller and pyritized. holotype, and is clearly defined back to ap- In the paratype, the anterior is flattened pendage 19. The legs on the left are within the dorso-ventrally and is complete or almost com- body margin but well-defined. There are one plete. The first appendages are terminal. The or two additional legs, appendages 20 and 21, second pair of appendages are smaller than the which are not exposed on the right. posterior appendages. The anterior of the ho- The legs taper from a wide base to a blunt lotype is crushed more laterally and is incom- tip and are approximately 2 mm long in the plete so we do not know the shape and location holotype. Some of the legs in the paratype are of the first appendages. longer, up to 3 mm, broader and less pointed. Discussion.-A vermiform animal like He- The paratype has one appendage with two lenodora inopinata with many pairs of ap- small (0.5 mm long) claws at the tip (P1. 3, fig. pendages and without a skeleton can be as- 4) and less well-preserved claws on other legs signed to only three existing taxonomic groups: in the left row (Text-fig. IB). These are on the polychaetes (Annelida), or the both halves of the concretion. The holotype or onychophorans of the Phylum Uniramia has no unambiguous claws. One leg has at its (Manton, 1972, 1977). When all the preserved tip two small grooves that may be molds of characteristics of H. inopinata are considered, the claws. classification is restricted to the onychopho- .-The cuticle is preserved as brown rans. patches with annuli (Text-fig. 1, A and B; P1. We cannot place H. inopinata with the 2, fig. 3). In the paratype, these patches have polychaetes because the appendages are not a metallic green luster when wet and are in parapodia. The appendages of H. inopinata part replaced by pyrite. Most of the patches are ventro-laterally placed like , not contain annulations, about 9 per segment. The lateral like parapodia. In addition, the para- crests of the annulations on the paratype have podia of the Mazon Creek polychaetes are pre- small cones spaced evenly 2-3 mm apart. Be- served with aciculae and setae and almost nev- cause of the regularity of the spacing of the er with definite outlines (Thompson and cones, these cannot be pyritic growths. Little Johnson, 1977; Thompson, 1979). Helenodora is seen of the cuticle on the legs. The paratype inopinata, to the contrary, has limbs without has a small patch of cuticle over appendage 11 aciculae or setae but with very definite out- (Text-fig. 1B) but this is poorly preserved and lines. These strong outlines are probably due shows no structure. to the greater thickness of the limbs compared Head.-The presumed anterior end (see to parapodia. In the very few cases above) is not well-preserved in either speci- seen by the senior author where parapodial men. In the holotype, the concretion split with outlines of Mazon Creek polychaetes are pre- the anterior tip still buried in the matrix. We served, the preservation of the entire poly- tried to excavate this matrix without success. chaete was extraordinary and the aciculae and The paratype appears to be more complete. setae were also preserved. If H. inopinata was The only parts missing may be the tips of the a polychaete, the strong outlines of the limbs first appendages. would indicate exceptional preservation and Each specimen has a dark brown patch near aciculae and setae would also be preserved. the anterior end which we have labeled "jaw?" Similarly, when polychaete aciculae and es- in Text-fig. 1. This patch in the holotype is pecially setae are not preserved, the faint trace shown enlarged in P1. 3, fig. 2 and exhibits of the worms indicate decay was far advanced

EXPLANATION OF PLATE 1 FIGS. 1,2-Helenodora inopinata n.gen., n.sp., holotype, FMNH PE 29049, part and counterpart of dorso-ventrally compressed specimen showing dorsal surface and right-lateral side with right legs outlined. 1, anterior is to the right, overhead lighting. 2, anterior is to the left, lighting from left. Bar , 10 mm. MAZON CREEK ONYCHOPHORAN 591

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TEXT-FIG.2-Reconstructions of A, Aysheaia pedunculata Walcott (from: Whittington, 1978). B, He- lenodora inopinata n.gen., n.sp. C, novae-zealandiae (from: Snodgrass, 1958). All three species are enlarged approximately x2. before preservation was complete. The speci- are 1 mm or less in length, clearly different mens of H. inopinata are not poorly preserved from the macroscopic animal H. inopinata. as the body outlines are clear and the cuticle The classification of H. inopinata in the is preserved in places complete with annula- subphylum Onychophora is compatible with tions and papillae. All the evidence indicates all preserved characteristics. The limbs are lo- the appendages of H. inopinata were lobo- bose. Helenodora inopinata has two terminal podia, not parapodia. claws which are approximately the same size Helenodora inopinata cannot be a tardi- and shape as living onychophoran claws (P1. grade as Delle Cave and Simonetta (1975) 3, figs. 4, 5). The trunk is annulated. When have suggested for Aysheaia. Tardigrades do preservation of the cuticle is good, small have lobopodia, but there the similarity ends. pumps which may be papillae are visible in Living tardigrades have only eight legs and rows on the crests of the annulations. The size each terminates in six claws. and shape of H. inopinata is similar to recent mouths are terminal. All known tardigrades onychophorans.

EXPLANATION OF PLATE 2 FIGS. 1-3-Helenodora inopinata n.gen., n.sp., paratype, FMNH PE 29050. 1,2, part and counterpart of dorso-ventrally compressed specimen showing ventral surface and outlining right legs, anterior is to the left in both figures, bar scales, 10 mm. 3, enlarged view of cuticle impres- sion showing transverse rows which once were papillated (arrows), bar scale, 1 mm. 594 IDA THOMPSON AND DOUGLAS S. JONES

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However, we do not feel that we can firmly Habitat.-Aysheaia pedunculata was al- place H. inopinata with the Onychophora. most certainly marine (Whittington, 1978) Helenodora inopinata may belong to an ex- while all living onychophorans are terrestrial tinct group. We are not sure about the details (Clark, 1915; Cuenot, 1949). Unfortunately we of the head. Helenodora inopinata may have do not know the habitat of H. inopinata. The had a jaw and ventral mouth, but the dark Mazon Creek locality contains a mixture of patches we call "jaw?" in Text-fig. 1 are poorly marine, freshwater, and terrestrial organisms preserved. The presumed anterior appendages (Richardson and Johnson, 1971). The more of both specimens are not well enough pre- southerly collecting sites, in particular Pit served to know for sure if these were antennae Eleven of the Peabody Coal Company where and oral papillae. both specimens of H. inopinata were discov- Our reconstruction of H. inopinata (Text- ered, contain mostly marine . How- fig. 2B) reflects our confidence in the mor- ever, an occasional , millipede, or am- phology of the trunk and limbs, but the an- phibian is found here also, along with many terior and posterior are dashed in to indicate terrestrial . uncertainty. For the reconstruction, we have The morphology of H. inopinata, when interpreted the specimens under the assump- compared to the marine Aysheaia and the ter- tion that they were onychophorans. The first restrial Peripatoides (Text-fig. 2), may show appendages of the paratype are assumed to be adaptations for terrestrial , but this is only the bases of terminal antennae; the second ap- speculation. For example, the shorter, more pendages are assumed to be oral papillae. closely spaced legs of H. inopinata and Peri- These assumptions are not inconsistent with patoides may be adaptations to terrestrial lo- the evidence, but we recognize the possibility comotion. The reduced number of claws may of other interpretations. reflect the increased ease with which a terres- We have included Whittington's (1978) re- trial as opposed to an aquatic organism can construction of the lobopod Ay- grip a horizontal substrate. The slimmer body sheaia pedunculata (Text-fig. 2A) for compar- and legs may facilitate gas exchange in air. ison with H. inopinata and a Recent onychophoran (Text-fig. 2C). In contrast to CONCLUSIONS the Recent onychophoran, A. pedunculata has 1) A new genus and species of lobopod fewer limbs, more claws on each limb, spines metazoan, Helenodora inopinata, is described on the legs, no terminal antennae, no oral pa- from the Middle Pennsylvanian Mazon Creek pillae, and a terminal mouth. Whittington beds of Northern Illinois. There are only two (1978) has removed A. pedunculata from the known specimens, each preserved in a siderite Onychophora because of these differences. concretion. However, he sees as a possibility the descent 2) The trunk and legs of the specimens are of both onychophorans and tardigrades from well-preserved, with patches of cuticle show- a group including A. pedunculata. Helenodora ing annulations and papillae. The legs were inopinata may also be a descendant of this short cones, terminating in two small claws. group. Whether or not it had reached the 3) Morphology of the head and tail are am- grade of Onychophora we cannot say for sure. biguous. Both specimens have suggestions of

EXPLANATION OF PLATE 3 FIGS. 1,2-Helenodora inopinata n.gen., n.sp. 1, Enlargement of anterior of holotype (P1. 1, fig. 1) with arrow indicating possible jaw, bar scale, 2 mm. 2, enlargement of impression of possible jaw from fig. 1, bar scale, 250 gxm. 3- sp. Two elements which comprise one half of the paired jaw system in a Recent onychophoran, anterior is to the upper right, SEM photomicrograph, bar scale, 100 ,um. 4-Helenodora inopinata n.gen., n.sp. Arrows indicate tips of paired claws located on the para- type (P1. 2, fig. 2), bar scale, 250 ,tm. 5-Peripatus sp. Paired claws from Recent onychophoran, anterior is to the left, SEM photo- micrograph, bar scale, 50 g/m. 596 IDA THOMPSON AND DOUGLAS S. JONES jaws near the tapered end. The paratype has Hutchinson, G. E. 1930. Restudy of some Burgess two pairs of terminal appendages that may be Shale fossils. Proc. U.S. Natl. Mus. 78:1-24. parts of antennae and oral papillae. 1969. Aysheaia and the general morphology of the Am. Sci. 267:1062-1066. 4) In all preserved characteristics, H. ino- Onychophora. J. Jaeger, H. and A. Martinsson. 1967. Remarks on classified with the pinata can be living ony- the problematic fossil Xenusion auerswaldae. chophorans. However, assignment to this Geol. For. Stockh. Forh. 88:435-452. group is made only tentatively because of the Johnson, R. G. and E. S. Richardson, Jr. 1966. ambiguity of the details of the head. A remarkable Pennsylvanian fauna from the 5) Helenodora inopinata is compared to Mazon Creek area, Illinois. J. Geol. 74:626-631. D. S. and I. 1977. Echiura from Aysheaia pedunculata and the Recent ony- Jones, Thompson. the Pennsylvanian Essex fauna of northern Illi- chophoran Peripatoides novae-zealandiae. nois. Lethaia 10:317-325. Characteristics shared with the terrestrial P. Manton, S. M. 1972. The of arthropo- novae-zealandiae but not with the marine A. dan locomotory mechanisms. Part 10. Locomo- pedunculata could indicate H. inopinata had tory habits, morphology and evolution of the adapted to a terrestrial habitat. However, H. hexapod classes. J. Linn. Soc., Zool. 51:203-400. . The functional inopinata comes from beds containing a mix- 1977. : habits, morphology, and evolution. Clarendon Press,, ture of freshwater, and terrestrial or- marine, Oxf., 527 p. ganisms. Pompeckj, J. F. 1927. Ein neues Zeugnis uralten Lebens. Palaontol. Z. 9:287-313. Richardson, E. S., Jr. and R. G. Johnson. 1966. ACKNOWLEDGMENTS Wormlike fossil from the Pennsylvanian of Illi- We thank Mrs. Helen Piecko of Chicago, nois. Science 151:75-76. -- Illinois for her generous donations and enthu- and . 1971. The Mazon Creek faunas. N. Am. Proc. siastic with this We also Paleontol. Conv., Chic., 1969, cooperation study. Part 1:1222-1235. H. B. S. thank Whittington, Conway Morris, Schram, F. R. 1973. Pseudocoelomates and a and F. R. Schram for comments on an earlier nemertine from the Illinois Pennsylvanian. J. Pa- draft of the manuscript. This paper has also leontol. 49:985-989. benefitted from the critical reviews of D. Baird and M. H. Nitecki. 1975. Hydra from the and A. G. Fischer. Illinois Pennsylvanian. J. Paleontol. 49:549-551. Snodgrass, R. E. 1958. Evolution of mechanisms. Smithson. Misc. Collect 138:1-77. REFERENCES Tarlo, L. B. H. 1967. Xenusion-onychophoran or coelenterate? Mercian Geol. 2:97-99. Bergstr6m, J. 1979. Morphology of fossil arthro- Thompson, I. 1979. Errant polychaetes (Annelida) pods as a guide to phylogenetic relationships, p. from the Pennsylvanian Essex fauna of northern 3-56. In, A. P. Gupta (ed.), Arthropod Phylog- Illinois. Palaeontogr., Abt. A. 163:169-199. eny, Van Nostrand Reinhold Co., N.Y. and R. G. Johnson. 1977. New fossil poly- Clark, A. H. 1915. The present distribution of the chaete from Essex, Illinois. Fieldiana Geol. onychophora, a group of terrestrial . 33:471-487. Smithson. Misc. Collect. 65:1-25. Walcott, C. D. 1911. Cambrian geology and pa- Cuenot, L. 1949. Les onychophores, p. 1-37. In, leontology no. 5, Middle Cambrian . P. Grasse (ed.), Traite de Zoologie, 6, Masson et Smithson. Misc. Collect. 57:110-144. Cie, Paris. . 1931. With explanatory notes by C. E. Res- Dechaseaux, C. 1953. Onychophores, p. 3-7. In, ser. Addenda to descriptions of Burgess Shale J. Piveteau (ed.), Traite de Paleontologie, 3, fossils. Smithson. Misc. Collect. 85:1-46. Masson et Cie, Paris. Whittington, H. B. 1978. The lobopod animal Delle Cave, L. and A. M. Simonetta. 1975. Notes Aysheaia pedunculata Walcott, Middle Cambri- on the morphology and taxonomic position of an, Burgess Shale, British Columbia. Phil. Aysheaia (Onychophora?) and of Skania (unde- Trans. R. Soc., Lond. B 284:165-197. Monit. Zool. Ital. 9:67- termined phylum). (N.S.) MANUSCRIPT RECEIVEDAUGUST 21, 1978 81. REVISED MANUSCRIPT RECEIVED AUGUST 8, 1979