Tracing the trilobite tree from the root to the tips: A model marriage of fossils and phylogeny

Lieberman, Bruce S.; Karim, Talia S.

doi:10.1016/j.asd.2009.10.004

Cited by 49 publications

(27 citation statements)

References 76 publications

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“…But with the notable exception of Eodiscina, Kobayashi, 1939, the stratigraphically old trilobite taxa are indeed almost universally micropygous. Basal trilobite phylogeny remains a matter of debate [102], but the basal split, as best supported would be among micropygous Olenellina [103] and all other trilobites, including a paraphyletic “Redlichiina” at the base [104]. The “redlichiine” trilobites equally are micropygous, while the isopygous Eodiscina are considered to branch off above, although some have suggested them to be derived from olenellines [105].…”

Section: Discussionmentioning

confidence: 99%

Arthroaspis n. gen., a common element of the Sirius Passet Lagerstätte (Cambrian, North Greenland), sheds light on trilobite ancestry

et al. 2013

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BackgroundExceptionally preserved Palaeozoic faunas have yielded a plethora of trilobite-like arthropods, often referred to as lamellipedians. Among these, Artiopoda is supposed to contain taxa united by a distinctive appendage structure. This includes several well supported groups, Helmetiida, Nektaspida, and Trilobita, as well as a number of problematic taxa. Interrelationships remain unclear, and the position of the lamellipedian arthropods as a whole also remains the subject of debate.ResultsArthroaspis bergstroemi n. gen. n. sp., a new arthropod from the early Cambrian Sirius Passet Lagerstätte of North Greenland shows a striking combination of both dorsal and ventral characters of Helmetiida, Nektaspida, and Trilobita. Cladistic analysis with a broad taxon sampling of predominantly early Palaeozoic arthropods yields a monophyletic Lamellipedia as sister taxon to the Crustacea or Tetraconata. Artiopoda is resolved as paraphyletic, giving rise to the Marrellomorpha. Within Lamellipedia, a clade of pygidium bearing taxa is resolved that can be shown to have a broadly helmetiid-like tergite morphology in its ground pattern. This morphology is plesiomorphically retained in Helmetiida and in Arthroaspis, which falls basally into a clade containing Trilobita. The trilobite appendages, though similar to those of other lamellipedians in gross morphology, have a unique outward rotation of the anterior trunk appendages, resulting in a ‘hard wired’ lateral splay, different to that observed in other Lamellipedia.ConclusionsThe combination of helmetiid, trilobite, and nektaspid characters in Arthroaspis gives important hints concerning character polarisation within the trilobite-like arthropods. The distinctive tergite morphology of trilobites, with its sophisticated articulating devices, is derived from flanged edge-to-edge articulating tergites forming a shield similar to the helmetiids, previously considered autapomorphic for that group. The stereotypical lateral splay of the appendages of lamellipedians is a homoplastic character shown to be achieved by several groups independently.

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Section: Discussionmentioning

confidence: 99%

Arthroaspis n. gen., a common element of the Sirius Passet Lagerstätte (Cambrian, North Greenland), sheds light on trilobite ancestry

et al. 2013

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“…Lieberman & Karim (2010) considered Proscharyia to be a separate phylogenetic branch of the Order Aulacopleurida, though directly related to the Scharyiidae and Brachymetopidae, a view previously discussed by Adrain & Chatterton (1993). Zhou & Zhou (2008) considered Radnoria to be a junior synonym of Niuchangella Zhang, 1974.…”

Section: Radnoria Carlsimentioning

confidence: 99%

The oldest brachymetopid trilobite record from the European peri-Gondwana

Pereira¹,

Silva²,

Pires³

et al. 2015

Bull. Geosci.

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“…Lieberman and Melott (2013) describe this increased risk of cladewide extinction as resulting in a "survival of the blandest" pattern as high volatility clades are weeded out over time while low volatility clades persist. The impacts of volatility seem to be particularly important during times of mass extinction, with high volatility clades, like ammonites and trilobites, suffering greater losses than their low-volatility contemporaries (Lieberman and Karim 2010). Interestingly, the reason trilobites, and also ammonites are no longer with us today, is likely because they evolved rapidly.…”

Section: Macroevolution: a Case Studymentioning

confidence: 99%

“…"For example, the trilobites appear to be harder hit by mass extinctions than their contemporaries (Lieberman and Karim 2010). In spite of their high levels of diversity, trilobites suffered major losses during the end Ordovician (Melott et al, 2004) and Late Devonian mass extinctions (McGhee 1996).…”

Section: Macroevolution: a Case Studymentioning

confidence: 99%

“…The early history of trilobite evolution shows a pattern of biogeographic differentiation which taken with other evidence suggests that there may have been some significant period of trilobite evolution before they actually appeared in the fossil record. Current estimates suggest that although the earliest trilobites appeared in the fossil record around 525 Ma they may have originated 550-600 Ma (Lieberman and Karim 2010). Paleontologists continue to investigate this trend looking for evidence of older trilobites and working to better constrain the timing of their origins.…”

Section: Trends/events In the Evolutionary History Of Trilobitesmentioning

confidence: 99%

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Beyond memorization: an intermediate-level paleontology activity that integrates anatomy, ecology, and macroevolutionary theory using trilobites

Casey

Lieberman

2014

Evo Edu Outreach

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Here we present a stand-alone, upper level undergraduate laboratory exercise that integrates organismal ecology and evolutionary concepts and minimizes the need for student memorization. This laboratory seeks to integrate both anatomical and conceptual content into paleontology lab pedagogy by demonstrating how taxon-specific anatomical information are the fundamental data by which scientists evaluate big picture questions related to the study of macroevolution and ecology. Real specimen photos are provided to familiarize students with a relatively limited suite of anatomical terms and taxonomic detail while allowing schools lacking large paleontology collections to participate in specimen-based inquiry. A matching exercise requires students to assign various trilobite morphologies to their interpreted ecological niches, thus reinforcing the students' new anatomical knowledge and helping students to distinguish between primary and secondary interpretation of scientific evidence. The use of trilobites as a macroevolutionary case study introduces students to questions still being actively investigated by scientists and provides an effective refutation of creationist arguments. By deemphasizing systematics and highlighting intriguing patterns from the recent published literature, this laboratory hopes to promote paleontology as a vibrant and relevant field, and avoid the misconception that paleontologists are simply stamp collectors, intent on naming and categorizing fossils. We hope that the broad implementation of this laboratory exercise will generate the data necessary to evaluate the validity of this approach and its ease of use in the classroom.Keywords: Macroevolution; Trilobita; Volatility; Ecological niches; Mass extinction Learning goals and pedagogyWe have developed a trilobite laboratory for college students; here we describe aspects and elaborate on the background and pedagogical philosophy behind the formulation of this lab. The complete version of the lab itself and the key are available as a pdf downloadz at the end of this article (Additional files 1 and 2). However, since the pedagogical and background elements pertaining to the development of the lab are not provided therein, we felt it important to present this information in the context of a broader discussion about the best way to teach paleontology and evolution to undergraduates. The trilobite lab we developed is intended for an upper level undergraduate paleontology course enrolling mainly sophomores and juniors who have already taken historical geology or its equivalent but may also be appropriate for introductory college biology or advanced high school biology courses provided that concepts such as geologic time, phylogeny, and trace fossils are familiar to students. It aims to comprise an exercise for one week in what would be a multi-week lab, though it can also serve as a standalone exercise as well. This lab will be particularly helpful to those institutions that lack a large teaching collection by providing color photographs ...

show abstract

Tracing the trilobite tree from the root to the tips: A model marriage of fossils and phylogeny

Cited by 49 publications

References 76 publications

Arthroaspis n. gen., a common element of the Sirius Passet Lagerstätte (Cambrian, North Greenland), sheds light on trilobite ancestry

Arthroaspis n. gen., a common element of the Sirius Passet Lagerstätte (Cambrian, North Greenland), sheds light on trilobite ancestry

The oldest brachymetopid trilobite record from the European peri-Gondwana

Beyond memorization: an intermediate-level paleontology activity that integrates anatomy, ecology, and macroevolutionary theory using trilobites

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