Franklin & Marshall College Franklin & Marshall College

Roger D. Thomas

ARTHROPODA: SUBPHYLUM ARACHNOMORPHA

 

CLASS TRILOBITA

Chancia - Arthropoda, Trilobita (cl.), Ptychopariida (ord.), Alokistocaridae
Cephalon, Pygidium BCTHZXQ - Jointed attachment to the thorax, anteriorly and posteriorly.
Eyes - Present throughout this family?
Librigenae BCVHZXR
Thorax BCWHZXS
Genal spines BCVGZXR

Ehmaniella - Arthropoda, Trilobita (cl.), Ptychopariida (ord.), Alokistocaridae
Cephalon, Pygidium BCTHZXQ - Jointed attachment to the thorax, anteriorly and posteriorly.
Eyes BCWKZXR - Lenses are solids. Data?
Librigenae BCVHZXR
Thorax BCWHZXS
Genal spines BCVGZXR

Elrathia - Arthropoda, Trilobita (cl.), Ptychopariida (ord.), Alokistocaridae
Cephalon, Pygidium BCTHZXQ - Jointed attachment to the thorax, anteriorly and posteriorly.
Eyes BCWKZXR - Lenses are solids. Data?
Librigenae BCVHZXR
Thorax BCWHZXS
Genal spines BCVGZXR

Elrathina - Arthropoda, Trilobita (cl.), Ptychopariida (ord.), Alokistocaridae
Cephalon, Pygidium BCTHZXQ - Jointed attachment to the thorax, anteriorly and posteriorly.
Eyes BCWKZXR - Lenses are solids. Data?
Librigenae BCVHZXR
Thorax BCWHZXS
Appendages Poorly preserved (B,E,C p. 160)

Hanburia - Arthropoda, Trilobita, Corynexochoidea?, Dolichometopidae?  Taxonomic assignment uncertain (Whittington, 1998)
Cephalon, Pygidium BCTHZXQ - Jointed attachment to the thorax, anteriorly and posteriorly. "probably lacked an eye lobe" "facial suture may have been marginal around the anterior portion of the cephalon" (Whittington, 1998, p. 675).
Librigenae BCVHZXR - "The dorsal portion of the free cheek...confined to the genal angle." (W, p. 675)
Hypostome BCTHZXR - "outline of displaced hypostome" (W, p. 675)
Thorax BCWHZXS - Six segments in most larger specimens.

Kootenia - Arthropoda, Trilobita (cl.), Corynexochida (ord.), Dorypygidae
Cephalon, Pygidium BCTHZXQ - Jointed attachment to the thorax, anteriorly and posteriorly.
Eyes BCWKZXR - Lenses are solids. Data?
Librigenae BCVHZXR
Thorax BCWHZXS
Genal spines BCVGZXR
Multiple spines BCWGZXR - Pleural and pygidial spines.
Appendages - Poorly preserved (B,E,C p. 160)

Naraoi - Arthropoda, Trilobita (cl.), Nektaspida (ord.), Naraoiidae
Anterior shield, Posterior shield BCTHZXS - "thin layer of rock that intervened between the overlapping shields...... as far forward as their junction......at the anterior margin of the posterior shield. (Whittington, 1977, p.418-420). Size range 9 to 41 mm long, attached dorsal shields without traces of appendages interpreted as moults (p. 418).
Spines BCVGZXR - "a postero-lateral spine on the margin of the anterior shield" (p. 420). Are these really rods or should they be regarded as plates?
Appendages BCWGZXQ - Including the pair of antennae.
Appendages BCWHZXQ

Olenoides - Arthropoda, Trilobita (cl.), Corynexochida (ord.), Dorypygidae
Cephalon, Pygidium BCTHZXQ - Jointed attachment to the thorax, anteriorly and posteriorly.
Eyes BCWKZXR - Lenses are solids. Data?
Librigenae BCVHZXR
Thorax BCWHZXS - "no evidence of a fulcral process.... articulating half-ring and flange." (Whittington, 1980, Palaeontology 23: p. 178).
Genal spines BCVGZXR
Multiple spines BCWGZXR - Pleural, pygidial, and appendage spines.
Appendages BCWGZXQ
Appendages BCWHZXQ

Oryctocephalus - Arthropoda, Trilobita (cl.), Corynexochida (ord.), Oryctocephalidae
Cephalon, Pygidium BCTHZXQ - Jointed attachment to the thorax, anteriorly and posteriorly.
Hypostome BCTHZXR
Eyes BCWKZXR - Lenses are solids. Data?
Librigenae BCVHZXR
Thorax BCWHZXS
Paired spines BCVGZXR - Genal and pygidial (fourth pair?) spines
Multiple spines BCWGZXR - Pygidial spines.

Pagetia - Arthropoda, Agnostida (ord.), Eodiscina (subord.), Pagetiidae
Cephalon, Pygidium BCTHZXQ - Jointed attachment to the thorax, anteriorly and posteriorly.
Hypostome BCTHZXR
Eyes BCWKZXR
Thorax BCVHZXS
Libriginae BCVHZXR
Spine BCTGZXR - Axial spines developed on occipital ring and terminating the axis of the pygidium.

Parkaspis - Arthropoda, Trilobita (cl.), Corynexochida (ord.), Dolichometopidae
Cephalon, Pygidium BCTHZXQ - Jointed attachment to the thorax, anteriorly and posteriorly.
Hypostome  ??
Eyes BCWKZXR - Lenses are solids. Data?
Librigenae BCVHZXR
Thorax BCWHZXS
Genal spines BCVGZXR

Peronopsis - Arthropoda, Trilobita (cl.), Agnostida (ord.), Spinagnostidae
Cephalon, Pygidium BCTHZXQ - Jointed attachment to the thorax, anteriorly and posteriorly.
Thorax BCVHZXS

Ptychagnostus - Arthropoda, Trilobita (cl.), Agnostida (ord.), Hastagnostidae
Cephalon, Pygidium BCTHZXQ - Jointed attachment to the thorax, anteriorly and posteriorly.
Thorax BCVHZXS

Spencella - Arthropoda, Trilobita (cl.), ptychoparioid
Cephalon, Pygidium BCTHZXQ - Jointed attachment to the thorax, anteriorly and posteriorly. Rasetti (1951; 1963).
Thorax BCWHZXS - Thorax of 14 segments (one specimen).

Tegopelte - Arthropoda, Trilobita (cl.), Tegopeltidae
Cephalic shield, Pygidium BDTHZXR - Exoskeleton thin, unmineralized......."not articulated at the transverse divisions" (HBW, 1985, J. Paleont. 59: p. 1251). Lack of overlap at edges of tergites: "The implication is that the dorsal exoskeleton was not articulated at these junctions, but rigid, though in such a large, unmineralized but thin dorsal shield there would be some flexibility." (HBW, p. 1273). "Large wrinkles..... are present on the left side of the cephalon and tergites" (HBW, p. 1258). "supposed tergite boundaries" interpreted as "folds formed during flattening of an undivided shield" (Ramsksld et al., 1996).
Thorax BDWHZXR - "lack of longitudinal and transverse furrows and of articulation between tergites" (HBW, p. 1254).
Appendages BCWGZXQ - Including antennae, walking limbs.
Appendages BCWHZXQ - Coxae, lamellae, etc. What does it mean, mechanically, to be a soft-bodied trilobite? Lack of articulation of elements of dorsal exoskeleton is not unique. See also Upper Cambrian genus Schmalenseeia (Whittington 1981, Geol. mag. 118: 591-602).

CLASS CHELICERATA

Sanctacaris - Arthropoda, Chelicerata (s.phyl.)
Head shield BCTHZXQ - Dome-shaped, with triangular lateral projections. Moulting inferred from arthropodan affinity; size of specimens 46 mm to 93 mm long.
Trunk BCWHZXS - Eleven tergites. "The anterior margin of each pleura curves posteriorly at its lateral extremity to meet the posterior margin at a high angle." (Briggs and Collins 1988, p. 787; see also Figs. 4 and 6, which appear to show distinctly overlapping tergites.)
Appendages BCWGZXQ - Raptorial rami and antenna-like rami. The latter are reconstructed with segments (Briggs and Collins, Plate 71, figs. 1-3).
Appendages BCWHZXQ - Lamellate rami of trunk limbs.
Spines, setae BCWGZXR - Spines on raptorial rami, setae on lamellate rami of trunk appendages
Telson BCTHZXQ - "paddle-like".

OTHER ARTHROPODS

Actaeus - Arthropoda, class uncertain (Whittington, 1981)
Cephalic shield BCTHZX(Q) - Very poorly defined in the single known specimen. No evidence bearing on rigidity, but Whittington's reconstruction shows a substantially domed structure. Posterior attachment unknown.
Trunk tergites BCWHZXS - "Along the right side of the trunk is a series of imbricated plates, each going below the one in front." Lateral parts of trunk tergites 4-6 interpreted as pleurae, but reconstruction (Fig. 132) shows no distinct differentiation of the lateral regions of the tergites, nor any marked differences among the forms of the 11 trunk tergites. (Whittington, p. 349)
Terminal plate BCTHZX(Q) - Description refers to a "terminal plate" which is said to be similar to that of Leanchoilia. Although very poorly defined, this structure appears to have been much broader and flatter than the "tail spine" later described by Bruton & Whittington (1983) for Leanchoilia.
Appendage lobes -  "The plates anterior to these pleurae [i.e. those associated with trunk tergites 1-3] .... may represent lobes of appendages." (W, p. 349). Plates posterior to tergite 6 are interpreted in the same way. However, neither in the text nor in the reconstruction (Figure 132) is a clear distinction maintained among tergites, lobes of appendages, and gill lamellae. Information on these structures is too limited to define them.
Anterior appendage BCWGZXQ - "The stout proximal portion is bent through appendage about 70¡at its midlength and obscurely jointed . . ." (W, p. 349).
"branches" BDVGZXR - "from the inner side of this portion of the appendage arise two long, slim, flexible branches"
Spines BCWGZXR - "distal end bearing a group of four curved spines" (W, p. 349).
Biramous appendages: inner branch BCWGZXQ - "an elongate lobe showing fragments of lamellae around the margin...below it...is a tapering jointed inner branch." Status of "elongate lobe" is unclear, but inner branch is a jointed set of rods.

Alalcomenaeus - Arthropoda, class uncertain (Simonetta, 1970; Whittington, 1981)
Cephalic shield BCTHZX(Q) - "undivided cephalic shield" (Whittington, p. 352). Nature of articulation with trunk not specified.
Trunk tergites BCWHZXS - "a trunk region of maore than 10 somites" "an imbricated series of right pleurae"(Whittington, p. 352)
Terminal plate BCTHZXQ - "terminal plate is paddle-shaped" (p. 352) Inferred to have been used in "steering and perhaps assisting in swimming" (W, p. 354). These functions would seem to require a jointed articulation with the trunk.
Appendage lobes - "Because they are below the cephalic shield they cannot be pleurae and are assumed to be gill lobes, though they show no trace of marginal lamellae" (W, p. 353). So, not hard parts.
Anterior appendage BDVGZXR - "long, flexible anterior appendage" (W, p. 354). "proximally broad and distally slim" (p. 352).
Biramous appendages: inner branch BCWGZXQ - "The tips of the inner branches project between these lobes . . . appear to have borne a formidable armature of opposed spines . . .joints are not seen in them in 155659 and only questionably on limb 10 of 155658" (W, p. 354). Note that the inner branch itself is referred to as a spine on p. 352: "Between successive lobes a backwardly curved spine projects . . ."
Spines BCWGZXR - "armature of opposed spines" present on each inner limb branch. See drawing (Figure 129) and reconstruction (Figure 133).

Burgessia - Arthropoda, class uncertain, Burgessiidae (fam.)
Carapace BCTHZXR - "some indication of an original convexity" but often wrinkled and distorted, so inferred to have been "extremely thin and only weakly sclerotized". Some evidence that thefirst three post-antennal somites formed a cephalic region (would also be BCTHZXR) and that "the dorsal cuticle [formed] a true carapace extending back over the trunk as a fold of cephalic cuticle." (Hughes, p. 420)
Trunk BCWHZXQ - Tapered, segmented, "no convincing evidence for the existence of any pleaural structures." "Slightly 'stepped' outline of the trunk region" in one specimen may be result of compaction of an annulated body. (p. 421)
Telson BCTHZXQ - Last trunk appendage appears to belong to the preceding somite.
Caudal spine BCTGZXQ - "point of flexure at the base of the caudal spine" (p. 427, see also joint implied in Fig. 6, p. 431).
Appendages, claws BCWGZXQ, Coxae BCWHZXQ - Uniramous antennae. Ten pairs of walking legs, three cephalic, seven trunk. Trunk appendages biramous, walking leg and gill.
Posterior trunk appendage BCVGZXQ - "a short uniramous spike-like structure" Exact nature rather uncertain. (p. 426)
Setae BCWGZXR - Present at joints between limb segments.

Emeraldella - Arthropoda, class uncertain, "arachnomorph" (Briggs et al.)
Cephalic shield BCTHZXS - "Overlap....between first tergite and cephalic shield was almost half the length of the tergite.... articulating flange" (Bruton and Whittington, 1983, p. 561).
Trunk tergites BCWHZXS - "Overlap between successive thoracic tergites....was almost half length of the tergite...
Doublure Labrum BCTHZXR - "A narrow doublure was also present on the lateral and anterior margins of the cephalic shield, from which the shield-shaped labrum extended back." (Bruton and W., p. 561).
Posterior spine BCTGZXQ - "The posterior spine was similar in length to the thorax...." Appears to be segmented in some specimens, not in others. "the spine is straight or only very slightly curved and apparently had limited flexibility" (Bruton and W., p. 561). Ploughing in search of food, "the posterior portion of the body, and the long posterior spine, could have been flexed upward to maintain balance" (Bruton and W., p. 567). Implies jointed articulation.
Biramous limbs BCWHZXQ BCWGZXQ - Plate shaped elements include the coxae. Podomeres of the walking limbs essentially articulating rods.
Spines BCWGZXQ - "Three long, curved spines are inserted into the distal podomere to form a foot" (Bruton and Whittington, p. 562).
Spines BCWGZXR - Margins of the coxae "bore overlapping spines that formed the gnathobase" (Bruton and Whittington, p. 562).
Antennae BCWGZXQ (BDVGZXR) - "The long antenna, having over 110 annulations...was evidently highly flexible." Bruton and W., p. 562 Here we consider the antenna as a multicomponent unit. We get (BDVGZXR) by considering the pair of antennae as a unit.

Habelia - Arthropoda, class uncertain (Whittington, 1981)
Cephalic shield BCTHZXQ - "cephalic shield a quarter-sphere in form .... appears to have been evenly convex" (Whittington, p. 343). This form requiressufficient rigidity to support the "dome". "Posterior margin was not straight, but curved forward..." (Whittington, p. 343). "shorter lateral portions of the first and second tergites, and the shape of the cephalic shield laterally allowed considerable movement between cephalon and trunk." (W, p. 345).
Doublure BCTHZXR - "there was a narrow doublure" (p. 343), shown without further comment in Fig. 77. Function may have been to act as a curved "girder", helping to support the head shield, but to see this structure as a "rod" stretches the defininition farther than we can accept.
Trunk BCWHZXS - "trunk of 12 tergites" (Whittington, p. 343) No mention of mode of attachment to one another or to cephalic shield, but drawings strongly suggest imbricate articulation (Figs. 93-94).
Posterior spine BCVGZXQ - "inserted into the posterior margin of the 12th tergite; no specimen shows evidence of flexure at this junction." (W, p. 344). Thespine shows an abrupt flexure at two-thirds or three-quarters of the length; this flexure is at a clearly defined line, and appears to have been a joint." (Whittington, p. 344). But, we are skeptical, as it is hard to imagine function of such a structure. Could this be brittle fracture in weaker. distal part of the spine, associated with compaction? Whittington (p. 343) notes that all known specimens appear to be preserved in a "lateral or slightly oblique" orientation. Not having seen the specimens, we have followed Whittington here.
Walking legs BCWGZXQ - Six pairs of "multi-jointed walking legs are long and stout", appear to be associated with first six thoracic segments. (W, p. 345). "At the tip is what appears in some specimens to be a single, blunt spine" (p. 345). These are regarded here simply as the terminal rods of the walking legs (see Figures 76, 77). "a lobed outer branch bearing lamellae around the margin, is associated with each walking leg." (W, p. 345). This comment and others referring to cephalic appendgaes suggest the presence of segments, some which may well have been plates. But, these have not been observed directly, so no plate segments are included here.
Antennae BCWGZXQ - One pair of cephalic appendages "farthest forward, were uniramous, setose at the joints, and may have been the antennae". (p. 344).
Spines BCWGZXR - Multiple short spines along margin of the posterior spine (Figure 130) and along margins of the curved pleural tips of the trunk tergites (p. 343).
Median "spines" BCTHZXR - Some specimens show blunt protrusions on the crest of each of the first three trunk tergites, interpreted by Whittington (p. 344) as "a blunt, thick median spine that bore elongate tubercles." Not sufficiently spinose (see reconstruction, Figure 130) to be rods, so treated here as subsidiary plates.

Helmetia - Arthropoda, class uncertain, "arachnomorph" (Briggs et al.)
Head shield, Tail shield BCTHZXS - "a thin, semitransparent shell" (Walcott, 1918). "The cuticle of the wide, flat exoskeleton was very thin." (Conway M. et al., 1982, Atlas). However, sharply defined forward-facing spines at each anterior corner and regular outline of carapace imply a rigid construction. Walcott's excellent Figure 8 shows distinct marginal overlap of thoracic segments and a similar junction at rear of head shield.
? Labrum BCTHZX_ - "A large oval structure projected beyond the margin of the headshield....may have been a labrum. Conway Morris et al. (1982). No data on attachment of ?labrum.
Thorax BCWHZXS - "six short, wide trunk divisions" (Conway Morris et al. (1882, Plate E, p. 12). Apparent imbricate overlap (see above).
Spines lateral BCVHZXR, terminal BCTHZXR - One pair of lateral spines on head shield, two pairs on tail shield, and a terminal spine on the tail shield.
Appendages - "limbs are poorly known. They consisted of rows of filaments attached to an axis..." Inadequate evidence of hard parts. No evidence of walking limbs preserved.

Houghtonites - Arthropoda, class uncertain. Mollisonia gracilis of Walcott (1912, p. 197-198). What author redscribed as Houghtonites ?
Cephalon BCTHZX(Q), Spines BCWGZXR - "One of the striking peculiarities of the transverse anterior merging of the cephalon into the short blunt spines projecting from it (Walcott, p. 197)". No evidence of eyes.
Thorax BCWHZXS - Seven segments, each with median ridge on the posterior half of the segment. Plausibly imbricate on basis of Plate 24, figure 5,
Pygidium BCTHZX(Q) - Eighth segment appears to be attached to the pygidium (Walcott, 1912, p. 198).
Librigenae - "raised line that may be the facial suture" Inadequate evidence of distinct structures.
Thorax BCWHZXS - "The thorax has seven transverse segments" "the segments terminate in blunt, falcate, slightly furrowed ends that overlap on the next posterior segment" (Walcott, 1912, p. 197).

Leanchoilia - Arthropoda, class uncertain (Bruton and Whittington, p. 577)
Cephalic shield BCTHZXQ - Mode of attachment to first tergite not specified, but tergites more clearly imbricate further back (Bruton and W., p. 570)
Tergites BCWHZXS - "The amount of overlap increases from the fifth tergite as these become fanned and directed backwards." (Bruton and W. p. 570).
Tail spine BCTGZXQ - "Movement between the tail spine and the trunk would have been possible in a dorsoventral plane but not laterally because of the surrounding eleventh trunk tergite." (Bruton and Whittington, p. 570).
Fringing spines, Spines on walking limbs BCWGZXQ - "fringing spines of the tail....were inserted in sockets..." (Bruton and Whittington, p. 571 and Plate 16, figure 98). "The leg branch was armed with a double row of spines along the inner surface." (p. 573).
"Snout" BCTHZXR - "the front of the cephalon is prolonged into a dorsally curved snout..." "The tip of the snout appears to have been a solid spine, while the base was hollow..." (Bruton and Whittington, p. 571). Reconstruction suggests a much less spine-like modification of the anterior part of the cephalon.
Great appendage BCWHZXQ - "consists of four parts". Podomeres 2, 3, 4 each extended as a long, flexible ramus. Basal portions of the podomeres are fairly short, tubular plates (Bruton and Whittington, p. 571-572).
Rami and claws BCWGZXQ - "terminating distally in three claws and an of great append. annulated, flexible ramus" (B and W. p. 572).
Biramous limbs BCWGZXQ - Podomeres of the walking limbs essentially articulating rods. "Filamentous gill" not definitively skeletonized.
Distal claw BCTGZXQ - On each walking limb, "the eighth podomere articulated with a stout distal claw..." (p. 573).

Molaria - Arthropoda, class uncertain (Whittington, 1981, p. 335)
Cephalic shield BCTHZXS - "Semicircular in outline....", (W., p. 337), form of a quarter-sphere (abstract). "sclerotized exoskeleton". Tergite behind the cephalon bears a flange forming an articulating surface like those between the trunk tergites (W. p. 337).
Trunk tergites BCWHZXS - Eight somites with dorsal tergites, with lateral doublure (W., p. 337).
Telson BCTHZX(S) - "subcylindrical telson, longer than any tergite". No data on mode of articulation with eighth tergite. (W. p. 338).
Terminal "spine" BCWHZXQ BCWGZXQ - Whittington's account of "segmentation" of the "spine" is ambiguous. "Joints" are seen in some specimens, not others, but curvature is supposed to have been limited, given the "evenly curved appearance" (p. 338). Jointed, not a spine, or flexible spine? Most distinct joints shown in Fig. 27 coincide with a distinct break in curvature. However, Fig. 46 shows joints regularly distributed along the whole length of the telson. Distal segments long relative to width (rods), proximal segments are short cylinders. Articulation: spine "inserted into the end of the telson".
Appendages: Biramous limbs. "tongue shaped outer
Coxa BCTHZXQ; Podomeres BCWGZXQ; Claws BCVGZXQ; Spines BCWGZXR
branch arose from the coxa, and bore a fringe of lamellae." Outer branch and coxa are enclosed by relatively complex "plates". Distal podomeres are cylindrical rods. "large coxa, five distal podomeres, and a pair of curved, terminal claws". Spines also occur on proximal podomeres.
Antennae BCWGZXQ - Antennae short, far forward, "and appear composed of many podomeres" (W. p. 338).

Mollisonia - Arthropoda, class uncertain. Assigned by Walcott (1912) to Trilobita, order Hypoparia
Cephalon, Pygidium, Librigenae BCTHZX(Q) - "Test thin with a minutely granular surface" (Walcott, 1912, p. 196). No evidence bearing on attachment to the thorax. "raised line that may be the facial suture" Inadequate evidence of distinct structures.
Thorax BCWHZXS - "The thorax has seven transverse segments" "the segments terminate in blunt, falcate, slightly furrowed ends that overlap on the next posterior segment" (Walcott, 1912, p. 197).

Saratrocercus - Arthropoda, class uncertain (Whittington, 1981, p. 347) Whittington decribes this taxon directly in terms of differences from Molaria, to which it is presumed to be closely related.
Cephalic shield BCTHZXS - Posterior margin of shield shows a darker band, interpreted as an articulating flange. Shows evidence of flattening, may have been as convex as that of Molaria. (W. p. 348)
Trunk tergites BCWHZXS - "Each of the nine trunk tergites shows a darker, posterior band . . . presumably where the articulating flange of the following tergite underlies it." (Whittington, p. 348).
Telson BCTHZX(S) - "Behind the ninth tergite is a short and narrow, apparently cylindrical segment, markedly narrower, shorter and less conspicuous than the telson of Molaria. (W. p. 348).
Terminal "spine" BCTGZXQ, BCWGZXR - "posterior spine is relatively short, narrow at the base", "does not show evidence of jointing" (Whittington 1981, p. 348). ". . terminating distally in a group of spines".
Anterior limb BCVGZXQ - "the large, anterior cephalic limb [jointed] is distinctive. (W, p. 348)
Lobed appendages - Imbricate lamellae inferred along posterior margins. One pair associated with cephalon and one with each subsequent tergite. In the apparent absence of walking limbs, these are inferred to have served in both respiration and swimming (rowing, if the reconstruction of Figure 131 is to be believed). (W, p. 348) Inadequate evidence of hard parts.

Sidneyia - Arthropoda, class uncertain. "falls within the arachnomorphs a large group of arthropods including the chelicerates and trilobites (Briggs et al. 1994)
Cephalon BCTHZXS - Cephalon strongly convex (Bruton, 1981, p. 628). "the back edge of the doublure would lie beneath or slightly in front of the ceplalon - first thoracic somite articulation. (p. 628). "line that functioned as a marginal suture during moulting . . . Evidence for this includes the recognition of empty skeletons or moults that lack this doublure." (p. 629). "articulation between the cephalon and the first thoracic somite . . . shows that there is considerable overlap of the latter. (B, p. 632).
Doublure BCTHZXR - "This line of contact is a flattened flange (cephalic flange) along the border of the dorsal cephalon and the ventral doublure. The clear line of separation between the latter further supports the fact that the doublure is a distince plate and not . . . the rolled continuation of the cephalon onto the ventral side." (B, p. 629).
Antennae BCWGZXQ - "firm point of attachment"; "directed laterally then curved forwards, and is clearly flexible"; "At the base of the antenna . . . some form of muscular attachment or part of the flexible intgement surrounding the base." "proximal segments twice as wide as long . . . remaining segments longer and slimmer distally". (p. 630)
Eye stalks - Any hard part? Insufficent information to characterize (# of elements? rigid/flexible?)
Thorax BCWHZXS - Nine somites. "Narrow area of overlap at the distal part of each somite." (B, p. 632)
Abdomen BCWHZXQ - "consists of three somites which form simple, articulated rings, . . " (B, p. 632)
Telson BCTHZXQ - "a fourth terminal plate or telson" (B, p. 633)
Uropods BDVHZXR - The "swimmerets" of the tail fan. "Paired uropods articulate with the posteriormost abdominal ring and together with the telson form a caudal fan." "broad and lobe-like, with an indented and plumose posterior margin. This was probably equally as thin and flexible as the lateral and posterior parts of the telson, but the anterior edge is thickened and thus stiffer . ." "freedom of movement difficult to demonstrate and none shows any angular displacement sideways from the telson." (Bruton, p. 633)
Walking legs BCWGZXQ, Coxa BCTHZXQ - "the leg is attached to an enlarged basal segment (coxa) consisting of a mesially directed lobe fringed with spines forming a gnathobase, and a lateral coxal bar which extends upwards and terminates with a curved distal flange." Bruton, p. 636. The jointed walking leg, consisting of seven podomeres (p. 637) is shown in Figure 108, p. 650.
Spines on coxa BCWGZXR - "the inner margin of the gnathobase . . bears a double row of spines." Bruton, p. 637
Spines on pomoderes BCTGZXR - "podomeres 2, 3 and 4 have a dorsal spine . ." (Bruton, p. 638)
Distal claw BCTGZXQ, spines BCVGZXR - "This long, incurved claw appears to articulate with podomere 7 and is flanked by shorter paired spines at the articulation. (Brunton, p. 638-639).
Setal spines BCWGZXR - "setal spines from the ventral (inside of the legs" (p. 639; see also Figure 108, p. 650)

Skania - Arthropoda, class uncertain. Regarded by Walcott as a trilobite (see Resser's note, in Walcott, 1931, p. 25)
Cephalic shield B(D)THZX(Q) - "Dorsal shield thin" (Walcott, 1931, p. 25) "spine-like extensions that are so tenuous as to suggest that the cephalic carapace was formed of a delicate membrane." (p. 26). Ambiguous. Does not function of attached spines require that this dorsal shield was more or less rigid? No data on mode of attachment to "posterior shield".
Spines B(C)VGZXR - "postero-lateral angles extended into spines" If so thin and delicate, must be flexible? But, what does this imply for function?
Labrum BCTHZXR - "a doublure to which a small elongate labrum is attached" (Walcott, 1931, p. 25).
"Thorax" BDWHZXR - Preservation of single illustrated specimen (Plate 21, fig. 1) suggests that the cephalic shield was more substantial than posterior dorsal shield, which was "elongate and formed of 14 or 15 fused segments with a more less distinctly marked border." But, preservation "leaves some doubt as to whether the posterior dorsal shield is formed of fused or free segments." (Walcott, 1931, p. 25).
Appendages BCW(G)ZXQ - "several thoracic endopodites out of place on one side, and other specimens show the proximal joint obscurely but sufficiently well to recognize them." (Walcott, 1931, p. 26).

Thelxiope - Arthropoda, class uncertain, closely related to Habelia (Simonetta, 1964, p. 222-223; Simonetta and LDC, 1975, p. 5-6)
Cephalic shield BCTHZXQ - "un cephalon assai grande . . . costituito da 7 segmenti post-orali" (Simonetta, p. 223). Articulation at posterior of cephalon is reconstructed to look much like that between each of the trunk segments in Figure 3. However, substantial articulation at this junction, such as Whittington infers for Habelia, would require a true joint here.
Trunk BCWHZXS - "Al cephalon seguono sei segmenti mobili." Overlap of tergites inferred from Figure 3.
Pygidium BCTHZX(Q) - "un pigidio formato dalla coalescenza dei tre ultimi metameri col telson." No reference to mode of articulation with trunk segments.
Posterior spine BCTGZXR - "La spina del telson lunghissima" (S, p. 223) No joint(s) recognized along this spine, which is shown as having been fused to the "pygidium" (Simonetta, p. 223 and Figure 3). Note contrast here with Habelia.
Median spines BCTGZXR - "sei [trunk] segmenti mobili ornati dorsalmente da un' enorme spina". One spine per segment, reconstructed as being much more elongated than those of Habelia.
Spines BCWGZXR - Blunt dorsal and marginal spines on the "pygidium". Three dorsal and two or three on each side

Yohoia - Arthropoda, class uncertain, Yohoiiidae (fam.)
Cephalon BCTHZXQ - Short shield, roughly square in plan view from above, arched over anterior portion of body. Assuming that the reconstruction is correct, it would have to be rigid to maintain this form. Whittington (1974, p. 8) found no antennules or compound eye (compare with Simonetta, 1970).
Trunk BCWHZXS - Fourteen somites, tergites of ten anterior "semitubular in cross-section, laterally extended as pleurae." "Their shape and the spaces between them allow a degree of flexibility...." (Whittington, p. 9). Implies that the elements themselves were rigid. "Each tergite, and the telson, was extended forward by a short articulating flange, which passed beneath the doublure of the preceding tergite..." Jointed or imbricate? If thoracic segments of trilobites are imbricate, so are these tergites.
Telson BCTHZXQ - Lobate in outline, maximum width at the rounded tip. Evidence of rotation (p. 10).
Spines BCWGZXR, Pleurae BCWHZXR, moveable spines BCWGZXQ - Short spines around posterior margin of the telson (p. 9). Pleurae "extended posteriorly as a short, blunt spine" (p. 9, flattened). "four terminal, movable spines" at extremity of "great anterior appendage" (Whit., p. 10).
Appendages BCVHZXQ, walking legs BCWGZXQ - Pair of great anterior appendages, formed largely of flattened plates. "three pairs of walking (?) legs beneath the cephalic shield." (Whittington, p. 11).

ECHINODERMATA

Gogia (?) - Class Eocrinoidea, Family Eocrinidae
Theca, stem ACWHLXR - Did these plates grow entirely by accretion, or was any resorption involved?
Brachioles ACWKLXQ, ACWHLXQ - Brachioles consist of biserial brachiolars which appear to be articulated solids. Food groove was protected by cover plates that were capable of being raised. Treatise S470.

Echmatocrinus - ?Class Crinoidea, Order Echmatocrinida (Sprinkle, 1973, 1995)
?Class Anthozoa, Order Octocorallia (Ausich & Babcock, 1998)
Calyx, stem ACWHLXR - If this was an echinoderm, the skeleton was internal; in this case, did the plates grow by accretion, or was any remodeling involved? If it was an octocoral, would the plates have been secreted as sclerites by mesenchymal cells (Brusca & Brusca, p. 230)? If so, they would be internal structures. According to Sprinkle, plates of the 'calyx' are sutured. Ausich and Babcock see them "abutting in some places and perhaps imbricating in others" (p. 196), and as "thin scales" (Diagnosis, p. 194).
Arms ACWHLXQ - Short, heavily-plated uniserial arms with about ten brachial plates. "These stand out in higher relief than other parts of the animal and were apparently the most rigid parts of the body." (Ausich and Babcock, p. 198). It is hard to see these plates as octocoral sclerites. Were these cylindrical in 3-D? They do appear to be jointed at "V-shaped indentations, whether articulated by ligament or muscle pads (Sprinkle, but see A&B, p. 199).

Walcottidiscus - Class Edrioasteroidea, Family Stromatocystitidae
Theca ambulacra ACWHLXR, ACWHLXS - Did these plates grow entirely by accretion, or was any resorption involved? Theca largely composed of non-imbricate plates as in Stromatocystites, but with imbricate plates around the margin.

Eldonia - ? Class Holothuroidea
Disc BDTGLXP - No hard parts. Holothuroid without spicules? Walcott (1911). See Clark (1913). "In Eldonia the disc was probably only lightly sclerotized, but cuticle accretion was clearly marginal..." "The accretional mode of growth implies a certain stiffness of the cuticle and, even if it was not mineralized and thereby flexible in Eldonia, its elasticity was definitely low." (Dzik et al, 1997, p. 390). Inferring the presence of a U-shaped gut, a lophophore, and an ectodermal, marginally accreted exoskeleton, Dzik (1991) interprets Eldonia as a lophophorate.

HEMICHORDATA

"Ottoia" tenuis - Assigned to class Enteropneusta (acorn worms) by Briggs et al. (1994). "Entirely unrelated to the priapulids" (Conway Morris, 1977, p. 85).
Hooks [BCWG(L)XP] - "its anterior end has a band of hooks" (Walcott, 1911, p. 130, original description) Species never figured, no evidence of mode of attachment. Embedded in soft tissue? Growth assumed to be by accretion, by default.

 

CLASS GRAPTOLITHINIA

Chaunograptus - ? Order Dendroidea Bulman includes in graptolite Treatise, but within "a large group of unclassified genera, some members of which may ultimately prove not to be Graptolithina..." Hydrozoa: "Grouped about a specimen of the spongeTupoia lineata Walcott are some rhabdosomes of a "graptolite" that quite obviously used the sponge to climb on." (Ruedemann 1931, p. 2). "all the species are repent upon foreign bodies..." "basal constriction of the thecae and the irregular angles of divergence of the thecae from the hydrocaulus . . . suggests relationship to the hydroids of the campanularid type." (Ruedemann 1931, p. 3; descr. hydrozoan).
Stipes BCWGMXR - Growth of individual thecae and stems is clearly accretionary, but the extension of a given stipe occurs as a unit construction. Graptolite rhabdosome is an exoskeleton according to Bulman (Treatise). Stems are "rods" but must have been hollow, with tissue inside.
Thecae BCWJLXR - Each individual cone grows by accretion.

CHORDATA

Metaspriggina? - Chordata. No evidence of hard parts. Very imperfectly known. (Briggs, Erwin, Collier, p. 197).

Pikaia - Chordata
Notochord ADTGNXP - "a prominent rod along the animal's back that appears to be a notochord, the cartilage-like stiffening organ..." (Conway Morris and Whittington, 1979, Scient. Amer. 241 (July, 1), p. 131). No direct evidence of growth mode. Remodeling inferred from supposed relationship.

NOT ASSIGNED TO MAJOR GROUPS

 

ANOMAOLOCARIDS

Amiella - Phylum uncertain, listed by B/E/C as an anomalocarid (f.)
Cephalothorax BDTH_X_ - "only one broken specimen of the dorsal shield is known". Portion preserved "has been turned about...loosened and displaced". Flexible by analogy with Anomalocaris, but no independent evidence. Walcott (1910, SMC 57: 27-28).
Trunk "traces of seven abdominal segments" (Walcott, 1910, p. 28). Published observations inadequate to characterize morphology.

Anomalocaris - Arthropoda, class Dinocarida and order Radiodonta of Collins (1996), Anomalocarididae (f.)
How did these animals grow? We were uncertain on the basis of our reading of Whittington and Briggs (1985). However, Collins (1996, p. 291) cites Briggs (1979) in support of "growth by molting, as shown by the numerous claw molts on Mount Stephen". Head "shield" BDTHLX_
"The cuticle appears to have been only lightly schlerotized, except for that of 'appendage F' and 'Peytoia'." Bluntly rounded anterior with evenly curved or irregular outline. "It is assumed that an irregular outline is the result of folding of a thin cuticle ......" (Whittington and Briggs, 1985, p. 581). Yet, the reconstructions show a box-like form. Supported by hydrostatic skeleton within? "the head of A. canadensis is much more extensible and flexible than previously realized." (Collins, 1996, p. 285). Collins interprets as "flexible cuticle".
Eye lobes, stalks BCVGLXR - The inferred eye ("no structure can be seen within it") is supported by a short stalk. (Whittington and Briggs, 1985, p. 581-582). "two large eyes on stalks" (Collins, p. 285).
Trunk BDWHLXQ - "a subparallel-sided region consisting of a series of plates ....." "The plates overlap each other, but not in the same sense." (Whittington and Briggs, 1985, p. 587).
Anterior flaps BDWHLXR - Semicircular, ventral flaps between the mouth and the attachment of the head to the trunk. Whittington and Briggs (p. 585) think that these and the lateral lobes are homologous. Overlap between flaps is great, but each is attached separately to a trunk somite (?).
Lateral lobes BDWHLXR - Thin lateral flaps or lobes, attached along the length of the trunk. Whittington and Briggs (p. 594-598) think these structures were flexible and used in underwater flying, by means of an anterior to posterior propulsive wave (p. 597). These leaf-like structures are reminiscent of structures seen among the Vendobionta.
Gills BDWHLXR - Sets of four laminae, emplaced below the dorsal surface of each somite (tergite?) (p. 597). Are these really skeletonized?
Appendage F BCVHLXR - First, basal segment of each of the two major basal segments feeding appendages. (See W&B, p. 600). These appear to have been attached without a joint to the doublure, in front of the mouth. By distinguishing these from the more distal segments, the consistent orientation and paired nature of the appendages are recorded.
Appendage F BCWHLXS - Short cylinders, apparently imbricate, giving distal segments the appendages their flexibility. Together, these appendages look as if they could have functioned as a 'clam-rake'. (See W&B, p. 600).
Appendage F BCWGLXR - Sturdy spines with a consistent orientation, spines one surely fused to each segment of the appendage.
'Peytoia' BCWH_XS - Circlet of overlapping jaw plates. Relatively = mouth, heavily schlerotized, presumably attached to plates thin doublure, so commonly detached as a unit. Walcott's isolated type specimen for Peytoia is twice the size of that which was dissected out in Anomalocaris. (Whittington and Briggs, p. 582). Did these grow by molting? Hesitate to assume because so unlike other arthropod feeding structures.
'Peytoia' BCWG_XR - Flattened spikes which project from the circle = mouth, of plates, into the central opening. Marginal teeth projections, integral parts of the plates. "clusters of tiny spines on the frontal surfaces of the four largest teeth (Collins, p. 285).
'Peytoia' BCWG_XP - Additional, more elongate teeth, aligned = mouth with side of central opening. "They may not extra teeth have been attached to the plates of the circlet, but to the walls of a buccal cavity." (Whittington and Briggs, p. 583).
Fantail BCWHLXP - "The dorsal tail is composed of three pairs of vanes attachen en echelon." (Collins, p. 285). Vanes must be more or less rigid; jointed and movable, or fixed firmly in place?

Hurdia - Arthropoda, class and family uncertain.
Carapace BDVH(Z)XQ - "only the valves of the carapace are known." "The test was quite thin, and readily compressed and distorted which causes considerable variation in the outline of the valves." Walcott (1912, p. 186). No direct evidence of form/definition of hinge. Briggs et al. (1994) list with anomalocarids.

Laggania - Arthropoda, class Dinocarida and order Radiodonta of Collins (1996), Anomalocarididae (f.)
=Anomalocaris nathorsti Whittington and Briggs, 1985
= Peytoia nathorsti Chen, Ramsksld and Zhou, 1994
Distinguished by Collins (1996, p. 290) on basis of "very different heads, with different positions of the eyes and slightly different jaws, and very different bodies with a fantail on A. canadensis and flexible rod supports of the lateral lobes in L. cambria ".
Head "shield" BDTHLX_
Eye lobes, stalks BCVGLXR
Trunk BDWHLXQ - "the metameric trunk"(Collins, 1996, p. 287).
Lateral lobes BDWHLXR - Collins (1996) treats the anterior "flaps" as an integral part of this series
Lateral lobe ADWG_XR - "linear, flexible nodular structures embedded supports in the body across the ventral midline area and embedded in the lateral lobes where they terminate in a thickened clublike end." "a flexible rod controlling the movement of the lateral lobe." (Collins, p. 288). Description implies that this was an internal structure. Does this mean that these were not molted? Varied interpretations of earlier authors, omitted from reconstruction of W&B (1985)
Gills BDWHLXR
Appendage F BCVHLXR - "Great claw" differs in detail from basal segments Anomalocaris but not in its components.
Appendage F BCWHLXS - distal segments
Appendage F BCWGLXR - spines
'Peytoia' BCWH_XS = mouth, plates
'Peytoia' BCWG_XR - "longest bifurcating teeth do not seem to = mouth, occur on either side of the wide teeth in teeth L. cambria specimens as they do in A. canadensis." Collins (1996, p. 290)
Fantail None in Laggania. Trunk lobes "taper ... back to a blunt posterior." (Collins, 1996, p. 287).

Proboscicaris - Arthropoda, class and family uncertain.
Carapace BCVH(Z)XQ - "The valves were doubtless joined by a membraneous hinge along the dorsal border as in Canadaspis . . . one specimen shows evidence of two valves preserved." "strongly concave in anterior region ...", "wrinkles subparallel to the ventral margin .... clearly due to flattening of the originally convex test." Rolfe (1962, p. 2).

 

OTHERS

Amiskwia - Phylum uncertain
No hard parts. Walcott (1911) thought he saw three spines. Interpreting these as buccal spines, he regarded this organism as a chaetognath. Subsequent authors ( Owre and Bayer, 1962; Conway Morris, 1977) have seen no spines.

Banffia - Phylum uncertain. Tentatively referred to Gephyrea by Walcott (1911, p. 130) An elongangated, worm-like animal with striking segmentation (Walcott's figures, Plate 21, figs. 5 and 6). "On one specimen
Hooks BCVG(L)XP - two rather strong hooks occur at the posterior end." (Walcott, p. 131).

Dinomischus - Phylum uncertain (new?), Dinomischidae (f.)
Calyx BDTJLXR - CM (1977, Palaeontology 20: 835) suggests that the calyx may have been "sufficiently pliable" to permit muscles to control shape. No clear evidence of more than one element forming the inverted cone that constitutes the calyx. No direct evidence of growth pattern; CM's comparisons with cnidarians and stalked entoprocts suggest accretion.
Bracts BCWHLXR - "They appear to have been rather rigid" (CM, p. 835). Mode of attachment to calyx is unclear. Are they discrete?
Stem BCTGLXR
Holdfast [BDTHNXR] - Not skeletonized? In his reconstruction, CM shows it "inflated to its maximum size". If it was skeletonized, how did this external, apparently membraneous structure grow?

Emmonsaspis - Phylum uncertain
"no evidence of a discrete central stem or rachis" CM (1993, Palaeontology 36: 600). Inadequate evidence of skeletal structure to assume any hard parts. Vendobiont?

Nectocaris - Phylum uncertain (Conway Morris, 1976)
Cephalic shield BCVH_XQ - "A small oval shield covered the posterior half of the head." "Dorsal part missing . . .presences of a hinge along the dorsum is hypothetical . ." (Conway Morris, p. 708). If it has a hinge, 'valves' must be sufficiently stiff to rotate about this hinge. If more nearly related to arthropods, growth by molting is plausible. If closer to chordates (Simonetta, see also Briggs et al. 1994, p. 209), this would be less likely. No direct evidence on growth.
Trunk - Apparently segmented, but Conway Morris infers that the animal may have "swum by rapid lateral undulations of the unsclerotized trunk." If this correct, no hard parts.
Long appendages - A pair of short, straight projections from the anterior end of the headshield are interpreted as apparently unjointed appendages. Insufficient information to characterize.

Oesia - Phylum uncertain. Interpreted as a tube-dwelling polychaete by Walcott (1911, p. 132-133). No hard parts apart from: "Traces of minute hooks at the anterior end have been observed in one specimen." "No two specimens are alike." (Walcott, 1911, p. 133). Inadequate information to characterize.

Opabinia - Phylum uncertain, paraphyletic arthropod stem-group? Sister group of Anomalocaris and arthropods (Budd, 1996, p. 11).
Cephalon BCTH(Z)XQ - No evidence of discrete structural subunits, apart from eye stalks, according to W (1975, p. 31). This a relatively complicated "plate", itself enclosing 3-D space. "Posterior margin of the head region is ill-defined" (W, p.31) but presumed to have articulated with trunk.
Eye stalks BCVG(Z)XR - Outer pair of eyes borne on "a short, broad stalk", "inner pair were borne on a much shorter base" (W, p. 32). Latter not enough differentiated to be recognized as stalks? No mention of attachment for median fifth eye. Treated as short rods (elevator function), rather than plates defining cylinders?
Eyes BCWK(Z)XR - Any true hard parts? "I have assumed each eye was compound" (Whittington, p. 32). Preserved essentially as blobs. Each eye had many solid lenses, fused in organic matrix?
Frontal process - Does the proximal portion of this process have any true hard parts? May be expanded or extended: "flexible but capable of limited rotation" (Whittington, p. 33). Hydrostatic? Numerous transverse grooves, striations.
Tip of frontal process BCWG(Z)X(P) - Up to a dozen paired larger spines, diverging process forward, with small spines at their bases (Whittington, p. 33). Embedded in soft tissue or fused together? Mechanical function of this device is problematic!
Trunk BCWH(Z)XR - Cuticle "appears to have been sufficiently rigid in life to have maintained the shape of the lateral lobes, gills, and blades of the tail fan." (Whittington 1975, p.31). "The axial region is divided into 15 segments...." (W 1975, p. 36), but "divisions of the trunk are impressed lines only..." (Briggs and W, 1987, p. 185). If these divisions are accepted as segments, then they must be fused. Preservation suggests limited articulation of trunk (Whittington, 1975, p. 40) No direct evidence of growth process; Whittington (1975, p. 31 sees all his specimens as adults.
Lateral lobes BDWH(Z)XR - "I consider that each lobe was thin and flexible". "The junction between axial region of the trunk and lateral lobe is not clearly defined, the one passing into the other." (Whittington, 1975, p. 37). Successive lobes overlap one another, but not in structural contact, so these are not imbricate. "the lobes indeed seem to attach along a mid-lateral line, as in Whittington's original reconstruction" (Budd, 1996, p. 5
Limbs BDWG(Z)XR - "conical, probably lobopod-like limbs" based on "mineralization associated with the internal cavities" as in other lobopods like Paucipodia and Aysheaia. Budd (1996, p. 7). Reconstructed as if cuticle was 'segmented' like a series of narrow rings, but no direct evidence of this. Supported by conical sheet of flexible cuticle?
Claws - Budd (1996, p. 6) postulates the presence of "sets of terminal claws" on the basis of "small mineralized patches" at the tips of putative lobopod limbs. We omit these here, in the absence of better definition of the form of these structures.
Posterior portion of trunk BCTH(Z)XQ - "Axial region of the posterior portion of the trunk appears to have been cylindrical" (p. 39). Step in profile suggests joint between main portion of trunk and undivided terminal section (Whittington, p. 36).
Tail fan BCWH(Z)XR - Three pairs of "blades", "thin, flexible and readily crushed" (Whittington, 1975, p. 39). But, attitude in reconstruction and use of the term blade suggests at least moderate rigidity. Budd (1996, p. 4) confirms this reconstruction, contra Bergstrom (1986).
Terminal spines BCVG(Z)XR - Pair of spines at posterior end of tail fan. (Whittington, 1975, p. 39 and fig. 82, p. 34).

"Platydendron" - Phylum uncertain. Simonetta and Delle Cave (1978) regarded this organism as a polyclad turbellarian, but this assignment is not followed by later authors (e.g. Briggs et al. 1994). No hard parts.

Pollingeria - Phylum uncertain. Assumed to have been a polychaete annelid by Walcott (1911, p. 125). He compares this large animal with Wiwaxia.
Scales BCWH__(S) - Only individual scales are figured by Walcott. "thin, smooth, elongate and variable in outline." "so radically different from thoseof Wiwaxia that they do not fall within that genus." (p. 125). Isolated scales are common, grouped together in only one specimen.

Portalia - Phylum uncertain. Regarded by Walcott (1918) as a holothurian; inference disputed by later authors (see Briggs et al. 1994, p. 93.) Stout trunk with a series of tentacle-like structures on either side. Walcott (1918, p. 6, figure 6) refers explicitly to these structures as tube-feet. Indistinct differentiation of structure at one end. (Briggs et al., 1994, p. 93). No evidence of hard parts.

Redoubtia - "An elongate, creeping holothurian" (Walcott, 1918, p. 5) "uncertain affinities", under study by SCM (Whittington, 1985) No hard parts evident in Walcott's excellent illustration (Fig. 5). Cf. Spriggina?

Worthenella - Phylum uncertain. Assigned to Polychaeta by Walcott (1911), not restudied since then. No hard parts? Worm-like animal with 46 or more segments. "tentacles represented by short, faint, jointed appendages extending forward from the front of the head." "strong parapodia divided into two filamentous branches" associated with "trunk" segments. These look for all the world like walking limbs (Walcott's figure 2, Plate 22).

 

SCLERITOME-BEARING ANIMALS

Chancelloria - ?Phylum Porifera. These may or may not be sponges. See discussion in Yi and Bengtson (1989), Fossils and Strata 24.
Axial ray ACTGLXR - Central ray extending up out of the plane of (sclerite) the lateral sclerites. Rod or solid? Not clear how elongate this was. Looks like a short cone in some illustrations, but Walcott (1920) refers to it as an axial ray. Growth presumably by accretion over entire surface.
Lateral rays ACWGLXR - Four to nine lateral rays, attached to the central disk well enough not always to be disaggregated. Burgess Shale species. C. eros has relatively long, slender rays, certainly rods.

Wiwaxia - Annelida, Polychaeta (cl.), Phyllodocida (ord.), Canadiacea (sf.)
Sclerites = paleae BCWHMYS - Conway Morris lays out evidence of moulting. Butterfield cites a reference to 'replacement' of small by larger paleae as modern polychaetes grow. Gruet reviews accounts of a serial pattern of addition and loss of paleae in Sabellaria. Thus, although growth involves moulting of individual paleae, growth occurs by serial addition. Note CM's account (p. 533) of an individual interpreted as crawling out of its exuvia. This is implausible, for a scale construction does not require simultaneous moulting of the whole skeleton. Paleae presumed to have moved through a series of positions from addition to a point at which they were shed. Anterior to posterior?
"Spines" BCWHMXS - CM (p. 537): number of spines appears to be correlated with body length, "suggesting that spines were added as growth proceeded." Growth in place or not?
? Neurosetae BCWGMXP - Probable neurosetae of Butterfield
Jaws BCVGZXQ - Rigid or flexible? CM describes them as being folded when retracted. Rods or solids? CM calls them 'bars', length only 50% greater than width. Moulting? No direct evidence, but number of teeth in small jaws of juveniles similar to number observed in larger specimens.
Teeth BCWKZXR - Solid, conical teeth fused to jaw plates.