Taylor, John D.

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Journal of the Arkansas Academy of Science Volume 22 Article 19 1968 Proetid Trilobite from the Boone Formation in Arkansas John D. Taylor University of Arkansas, Fayetteville Follow this and additional works at: https://scholarworks.uark.edu/jaas  Part of the Paleontology Commons Recommended Citation Taylor, John D. (1968) "Proetid Trilobite from the Boone Formation in Arkansas," Journal of the Arkansas Academy of Science: Vol. 22 , Article 19. Available at: https://scholarworks.uark.edu/jaas/vol22/iss1/19 This article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able to read, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking prior permission from the publisher or the author. This Article is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the Arkansas Academy of Science by an authorized editor of ScholarWorks@UARK. For more information, please contact scholar@uark.edu. 102Arkansas Academy of Science Proceedings, Vol. 22, 1968PROETID TRILOBITE FROM THE BOONEFORMATION IN ARKANSASJohn D. Taylor*University of ArkansasA chert fragment from the Boone Formation, Rago, BentonCounty, Arkansas contains fourincluding the glabella, pygidium,was collected by Dr. Burnal RayCollege, Cape Girardeau, Missouridisassociated parts of a trilobiteand both free cheeks. The noduleKnox of Southeast Missouri Statein the NW 1/4, Section 5 T. 20 N.,R. 30 W. when he was a graduate student at the University of Ar-kansas. He kindly presented the specimen to the Department of Ge-ology. The author wishes to extend appreciation to Dr. James H.Quinn, University of Arkansas for his cooperation in the prepara-tion of the description of the trilobite which appears to belong to ataxon new to science. The trilobite has been described and the decrip-tion willbe published in the Journal of Paleontology or other suit-able journal. The drawing (Plate 1, Figure 2) was made by RobertHandford and the photographs (Plate 1, Figures 1& 2) by JamesEdson. Both are graduate students in Geology at the University ofArkansas.Superfamily PROETACEA Salter, 1864Family Proetidae Salter, 1864Subfamily (Uncertain)The trilobite has an elongate and elliptical exoskeleton and anopisthoparian suture. The length (sagittal) of the cephalon is aboutone half the width, (transverse). The broad flat cephalic portioncontrasts with the smaller pygidium.The free cheeks have a flattened exterior border which is con-vex at the extremity. There are more than six striations that extendfrom the anterior part of the cephalon to the end of the genal spine.Also the genal spine has moderate length. A prominent arcuate ridgerises steeply above the flattened border. The small to medium-sizedeyes which are close to the glabella project above the raised area. Thepalpebral lobes extend laterally above the eyes.The glabella is broad, parallel-sided, and rounded anteriorlyand in cross-section exhibits moderate relief. The lateral preoc-cipital lobes are large and prominent features. There are numerousglabellar furrows present but the number is not equal on both sides.The glabella appears to have been crushed slightly; thus some ornone of the glabellar furrows may be original features.•Instructor of Geology102Journal of the Arkansas Academy of Science, Vol. 22 [1968], Art. 19Published by Arkansas Academy of Science, 1968103'«•iProetid Trilobite from ArkansasThe pygidium has a semi-circular and moderately convex shapewith the length about one half the width. There is a well definedposterior border with more than ten striations. The axis is stronglyraised and extends almost to the border. The axial and pleural ribsare also prominent features.Remarks: There are reasons for supposing the disasssociatedparts represent a single trilobite. First, they are similar in size.Second, presence of the pair of free cheeks suggsts a single indi-vidual. Third, the parts can be assembled into an acceptable cephalonand reconstruction. A question does arise however; why are thethoracic segments not present? Also a rounded depression near theglabella is unidentified. (Plate 1, Figure 1)Repository: The specimen described here L-229 is in the Uni-versity of Arkansas Collection and recorded in the Geology Depart-ment Catalogue of Invertebrate Fossils at the University of Arkan-sas.REFERENCEHarrington, H. J., and others, 1959, Arthropoda 1, pt. O of Treatiseon invertebrate paleontology: Geol. Soc. America and Univ.Kansas Press, 560 p.103Journal of the Arkansas Academy of Science, Vol. 22 [1968], Art. 19https://scholarworks.uark.edu/jaas/vol22/iss1/19104I*I|Arkansas Academy of Science ProceedingsPLATE 1Figure 2EXPLANATION OF PLATE 1Figure 1. Chert fragment with four disassociated parts.Free CheeksRight—Sagittal, 43 mm; transverse, 23 mm.Left—Sagittal, 43 mm; transverse, 20 mm.GlabellaSagittal, 22 mm; transverse, 24 mm.PygidiumSagittal, 21 mm; transverse, 38 mm.Figure 2. Reconstruction104Journal of the Arkansas Academy of Science, Vol. 22 [1968], Art. 19Published by Arkansas Academy of Science, 1968

Proetid Trilobite from the Boone Formation in Arkansas

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Journal of the Arkansas Academy of ScienceVolume 22 Article 191968Proetid Trilobite from the Boone Formation inArkansasJohn D. TaylorUniversity of Arkansas, FayettevilleFollow this and additional works at: http://scholarworks.uark.edu/jaasPart of the Paleontology CommonsThis article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able toread, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking priorpermission from the publisher or the author.This Article is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the Arkansas Academyof Science by an authorized editor of ScholarWorks@UARK. For more information, please contact scholar@uark.edu, ccmiddle@uark.edu.Recommended CitationTaylor, John D. (1968) "Proetid Trilobite from the Boone Formation in Arkansas," Journal of the Arkansas Academy of Science: Vol. 22 ,Article 19.Available at: http://scholarworks.uark.edu/jaas/vol22/iss1/19102Arkansas Academy of Science Proceedings, Vol. 22, 1968PROETID TRILOBITE FROM THE BOONEFORMATION IN ARKANSASJohn D. Taylor*University of ArkansasA chert fragment from the Boone Formation, Rago, BentonCounty, Arkansas contains fourincluding the glabella, pygidium,was collected by Dr. Burnal RayCollege, Cape Girardeau, Missouridisassociated parts of a trilobiteand both free cheeks. The noduleKnox of Southeast Missouri Statein the NW 1/4, Section 5 T. 20 N.,R. 30 W. when he was a graduate student at the University of Ar-kansas. He kindly presented the specimen to the Department of Ge-ology. The author wishes to extend appreciation to Dr. James H.Quinn, University of Arkansas for his cooperation in the prepara-tion of the description of the trilobite which appears to belong to ataxon new to science. The trilobite has been described and the decrip-tion willbe published in the Journal of Paleontology or other suit-able journal. The drawing (Plate 1, Figure 2) was made by RobertHandford and the photographs (Plate 1, Figures 1& 2) by JamesEdson. Both are graduate students in Geology at the University ofArkansas.Superfamily PROETACEA Salter, 1864Family Proetidae Salter, 1864Subfamily (Uncertain)The trilobite has an elongate and elliptical exoskeleton and anopisthoparian suture. The length (sagittal) of the cephalon is aboutone half the width, (transverse). The broad flat cephalic portioncontrasts with the smaller pygidium.The free cheeks have a flattened exterior border which is con-vex at the extremity. There are more than six striations that extendfrom the anterior part of the cephalon to the end of the genal spine.Also the genal spine has moderate length. A prominent arcuate ridgerises steeply above the flattened border. The small to medium-sizedeyes which are close to the glabella project above the raised area. Thepalpebral lobes extend laterally above the eyes.The glabella is broad, parallel-sided, and rounded anteriorlyand in cross-section exhibits moderate relief. The lateral preoc-cipital lobes are large and prominent features. There are numerousglabellar furrows present but the number is not equal on both sides.The glabella appears to have been crushed slightly; thus some ornone of the glabellar furrows may be original features.•Instructor of Geology102Journal of the Arkansas Academy of Science, Vol. 22 [1968], Art. 19Published by Arkansas Academy of Science, 1968103'«•iProetid Trilobite from ArkansasThe pygidium has a semi-circular and moderately convex shapewith the length about one half the width. There is a well definedposterior border with more than ten striations. The axis is stronglyraised and extends almost to the border. The axial and pleural ribsare also prominent features.Remarks: There are reasons for supposing the disasssociatedparts represent a single trilobite. First, they are similar in size.Second, presence of the pair of free cheeks suggsts a single indi-vidual. Third, the parts can be assembled into an acceptable cephalonand reconstruction. A question does arise however; why are thethoracic segments not present? Also a rounded depression near theglabella is unidentified. (Plate 1, Figure 1)Repository: The specimen described here L-229 is in the Uni-versity of Arkansas Collection and recorded in the Geology Depart-ment Catalogue of Invertebrate Fossils at the University of Arkan-sas.REFERENCEHarrington, H. J., and others, 1959, Arthropoda 1, pt. O of Treatiseon invertebrate paleontology: Geol. Soc. America and Univ.Kansas Press, 560 p.103Journal of the Arkansas Academy of Science, Vol. 22 [1968], Art. 19http://scholarworks.uark.edu/jaas/vol22/iss1/19104I*I|Arkansas Academy of Science ProceedingsPLATE 1Figure 2EXPLANATION OF PLATE 1Figure 1. Chert fragment with four disassociated parts.Free CheeksRight—Sagittal, 43 mm; transverse, 23 mm.Left—Sagittal, 43 mm; transverse, 20 mm.GlabellaSagittal, 22 mm; transverse, 24 mm.PygidiumSagittal, 21 mm; transverse, 38 mm.Figure 2. Reconstruction104Journal of the Arkansas Academy of Science, Vol. 22 [1968], Art. 19Published by Arkansas Academy of Science, 1968

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Proetid Trilobite from the Boone Formation in Arkansas

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